bluuebunny/crossref_metadata_2025 huggingface dataset:
Travel, Tourism and the Environmental Challenges
Authors: Somerville Hugh
Published: January 2007

Travel and tourism have historically faced environmental challenges ranging from the impact of aircraft noise, largely at major departure airports, through provision of infrastructure at destinations, to interaction with communities and wildlife. The emerging challenge for air transport is the contribution of gases emitted by aircraft engines to the greenhouse effect and climate change. This is a relatively recent area for public attention and, while progress may seem slow to some observers, a number of options are under active study. Aviation will remain an essential part of the world's communication and transportation network but growth will increasingly be linked to solutions to these environmental challenges.
The Difficult Part is Yet to Come: Profit Rather than Traffic Alone Remains the Key to Airline Prosperity
Authors: Tarry Chris
Published: January 2007

Despite the first signs of a recovery in passenger traffic, significant challenges remain for the airline industry if it is to produce the returns that will make it attractive to the providers of capital at an acceptable cost. Although there appears to be a better balance between demand and supply, the industry remains in a situation of effective disequilibrium and needs to further reduce its cost base against the background of continuing real excess capacity. With the recovery in traffic the ability of management to continue to make change will become more difficult. The change in the competitive environment in Europe provides both challenge and opportunity. The risk is that the industry will become even less attractive to the providers of capital.
E-Tourism Developments in Greece: Information Communication Technologies Adoption for the Strategic Management of the Greek Tourism Industry
Authors: Buhalis Dimitrios , Deimezi Ourania
Published: January 2007

Information communication technologies (ICTs) have revolutionised the travel industry in the last decade. E-tourism reflects the digitalisation of all processes and value chains in the tourism, travel, hospitality and catering industries. It emerges as a term describing the entire range of applications of ICTs on tourism and the implications for the tourism value chain. Major opportunities and challenges have emerged and need to be addressed by all industry players. The level of e-tourism developments, however, varies between regions, countries and continents. The key objective of this research has been to examine the e-tourism developments in Greece as a country that is gradually embracing e-commerce. In particular the research examines the level of ICT diffusion in small and medium-sized tourism enterprises (SMTEs) as well as whether the level of online presence is sufficient to make up for the lack of a destination management system (DMS). Results indicate that the Greek online travel market is at the early stages of its e-commerce deployment, but that it demonstrates great potential for further e-tourism developments. The low level of cooperation between SMTEs, however, and the serious doubts about the ability of the National Tourism Organisation to coordinate the destination makes the prospect of a DMS development in Greece doubtful. The research concludes that ICT-enabled local cooperation can potentially assist SMTEs to enhance their competitiveness and increase their global presence.
Paradigm Shifts: National Tourism Organisations and Education and Healthcare Tourism. The Case of Singapore
Authors: Henderson Joan C.
Published: January 2007

This paper examines the changing role of national tourism organisations (NTOs) with particular reference to the case of the Singapore Tourism Board (STB). Problems and opportunities confronting NTOs are examined and some trends in marketing and product development are identified. Education and healthcare are attracting increasing interest and acquiring heightened priority, a process which requires a reassessment of definitions of tourism and the responsibilities of tourism boards. While both spheres are of commercial significance, they also pose considerable challenges for NTOs unaccustomed to working in these areas.
Stigma in Food Service Work: How it Affects Restaurant Servers' Intention to Stay in the Business or Recommend a Job to Another
Authors: Wildes Vivienne J.
Published: January 2007

Researchers have separately discussed the relationships between stereotype behaviour and behavioural intent. Other researchers have described the negative image of service work. The research for this study explored the notion that occupational stigma caused people to leave their jobs as restaurant servers.

Two hundred and forty-one restaurant servers completed the Stigma Consciousness Questionnaire (SCQ) to provide mean scores on both individual and group levels for the expectation of being stereotyped because of their job as food servers. Regression analysis provides data indicating that restaurant servers who feel stigmatised because of their work will not only leave the restaurant industry, but also will not recommend a job in the restaurant industry to a friend or family member.

Additional information points to studies that show 70 per cent of those under the age of 36 intend to leave the restaurant industry within two years; that 30 per cent of all respondents to the survey intend to stay in the restaurant industry for more than five years; and that 27 per cent categorised their job as professional.

Recommendations from this study suggest that managers create a campaign to promote the positive attributes of work in the food service industry to help overcome employee attrition. It is also suggested that those who are high in stigma consciousness who also intend to stay in the restaurant industry be recruited as spokes-people for the industry.
A Failure of UK Travel Agencies to Strengthen Zones of Tolerance
Authors: Gilbert David , Gao YingFei
Published: January 2007

Companies in all industries face problems pertaining to the issue of retaining customers and securing satisfaction through service quality management. The repeat purchasing behaviour at an individual level is affected by the level of a customer's ‘zone of tolerance’; a term not always fully understood. The purpose of this study is to examine the relationships that customer tolerance has with customer experience, brand trust and customer emotions for travel agency businesses. Customers who have had recent experience with the travel agencies were sampled from two UK travel agencies situated in London and Guildford. One hundred and twenty customers were surveyed face to face through means of a questionnaire. The results utilising Spearman Ranked Order correlation showed that there is a relationship between customer tolerance and customer experience. However, it was found there is no relationship between customer tolerance and customer emotion. In addition, the tests revealed that there is no relationship between customer tolerance and brand trust. The conclusion is that travel agencies are failing to keep in mind the importance of carefully handling customer tolerance and understanding the level of customer tolerance and its influence.
Opportunities and Constraints of Heritage Tourism in Hong Kong's Changing Cultural Landscape
Authors: Li Yiping , Lo Lap Bang Raymond
Published: January 2007

This study investigates the opportunities and constraints for heritage tourism development in Hong Kong through a case study. It aims to address the urgent need of heritage conservation against the city's ever-changing cultural landscape. The Market Appeal-Robusticity Matrix is used to assess 19 heritage assets in the Kam Tin area of the New Territories. The results suggest there is an increasing interest from both the government and general public in cultivating the city's heritage resources for tourism. Such an interest offers tremendous opportunities for the industry development. To appreciate the opportunities fully, however, appropriate strategies must be adopted in order to reduce the constraints that appear at two major levels
Cultural Influences on Ethical Decisions of Students Enrolled in European Hospitality Programmes
Authors: Brymer Robert A. , March Lynda , Palmer Michael , Schmidgall Raymond S.
Published: January 2007

This study focuses on how students at European hotel schools respond to ten ethical scenarios. Participants indicated whether the action posed was ethical, not ethical or not a question of ethics. Further, they indicated several factors influencing their ethical beliefs. Responses from students from European countries were compared to responses of students from Asian countries. The top three factors influencing both groups were parents, close friends and management courses. Only two of the ten scenarios were evaluated differently by the two groups.
Current Issues in the Global Hospitality Industry
Authors: Duncan Tara
Published: January 2007

This paper aims to highlight the current issues of most concern for the hospitality industry worldwide. By examining a number of hospitality and hotel association websites from around the world, eight main areas of concern for the hospitality industry were highlighted and examined in more detail. These areas included employment issues, taxation levels and environmental issues. The paper concludes by recognising both the powerful position many of these associations now hold on a national and sometimes international scale and the global nature of many of the main issues of concern for the hospitality industry
The Impact of the Internet on Travel Agencies in Taiwan
Authors: Bennett Marion M. , Lai Chi-Wen Kevin
Published: January 2007

Travel and tourism-related products and services are highly compatible with the internet with the result that travel and tourism is one of the highest revenue-generating sectors of the internet. The rapid growth of the internet is having an impact on the distribution of travel services and has heightened speculation about the potential for disintermediation of the travel agent. This research investigates the impact of the internet on the distribution of travel services and the extent to which it has influenced travel agencies by focusing on Taiwan, a technologically advanced country and one which has witnessed rapid growth of the internet. Employing a combination of a quantitative questionnaire administered to 438 travel agencies and personal in-depth interviews, the research found that travel agencies in Taiwan generally regard the internet as an effective tool for their business. Most agencies have adopted the internet in their daily operations and some have provided e-commerce services on the internet. Although travel agencies are affected by e-commerce services, the effect is not found to be significant. Equally, no significant difference was apparent between company size and classification in terms of the effect of ecommerce travel services on travel agents. Travel agencies agreed that commission cutting by suppliers was a threat but disagreed that disintermediation would occur, although booking offices were seen to be at risk. The research identified two principal future roles for travel agents: first, the need for them to reposition themselves as travel consultants and secondly, the need for them to become more technologically orientated. Finally, seven key strategies were suggested for Taiwan's travel agencies to ensure survival.
The Impact of Information Technology on Future Management of Lodging Operations: A Delphi Study to Predict Key Technological Events in 2007 and 2027
Authors: Singh A.J. , Kasavana Michael L.
Published: January 2007

This research study is part of a comprehensive Delphi study conducted by the faculty of The School of Hospitality Business at Michigan State University. The purpose of the research was to enable expert panellists to project the likelihood of specific events in the future of the lodging industry. This paper presents a summary of the key prognostications of a select panel of experts relative to the impact of information technology on the management of operations in the lodging sector in years 2007 and 2027. In general, panellists agreed future IT applications are likely to rely on a wireless infrastructure that provides cost savings through improved efficiencies and effectiveness. As online purchasing, cashless payments, handheld devices and remote monitoring algorithms become more commonplace, the industry will be better able to exceed guest expectations through enhanced customer relationship management, comprehensive application software and streamlined property management systems.
Understanding Resort Visitors through Segmentation
Authors: Inbakaran Robert , Jackson Mervyn
Published: January 2007

Tourist hotel resorts have been considered as indispensable elements in the major tourism industry component of accommodation for several decades. Tourist hotel resorts are sought after by various segments of domestic and overseas tourists all over the world for various holiday purposes. There have been several focused tourism research contributions over the last two decades about their location, life-cycle stages, service quality and management. Few researchers, however, have focused their research on the resort hotel guests' resort selection preferences, satisfaction by resort service, opinion on resort holiday and preference for quality of resort guest activities.

This paper tries to fill this vacuum in the resort tourism literature by exploring the visitors' views on resort selection, satisfaction, opinion and preferences. The research attempted to profile 776 visitors holidaying in resorts in selected resorts of Australia through a well-structured, four-page questionnaire divided into five parts containing 18 questions focusing on their reasons for resort selection, resort satisfaction, resort opinion and resort preferences under subtitles. The research also focused on their gender, age, level of education, occupation, life-cycle category, residency, nationality, postcode, years of patronisation, intimate selection choices and willingness to recommend their experiences.

An attempt was made to profile the resort visitors through a cluster analysis in order to understand the underlying dimensions on the basis of the above-mentioned factors, segmenting them into identifiable groups. Four discernable clusters of resort visitors and their distinguishing characteristics were identified on the basis of their demographics. Further, through a one-way ANOVA analysis the clusters are compared with each other for further understanding and clarity. The results shows that the gender factor does not have much influence whereas life-cycle, education and age have considerable influence in segmenting the resort clientele. The four clusters were correlated with the selection, satisfaction, opinions and preferences. The results will be discussed in terms of future resort developments, themes, generating resort activities focusing on young families and service quality.
Responding to Natural Disasters: Managing a Hotel in the Aftermath of the Indian Ocean Tsunami
Authors: Henderson Joan C.
Published: January 2007

The case describes the experiences of the General Manager of a luxury resort hotel on the Thai island of Phuket in the days immediately following the Indian Ocean tsunami at the end of 2004. Although the property escaped physical damage and there were no fatalities among residents and staff, the management had to deal with an unprecedented crisis caused by disruption to the tourism industry in the destination as a whole and a dramatic fall in arrivals. Recovery efforts are outlined and reference is made to longer-term impacts on business and the challenges of restoring confidence and returning to normality. Issues arising from the case are suggested in a final list of questions for discussion.
Advertising in Low and High Involvement Cultural Tourism Attractions: Four Cases
Authors: Kantanen Teuvo , Tikkanen Irma
Published: January 2007

In Finland almost 10 million tourists visit cultural attractions every year, which makes cultural tourism a considerable part of the tourism industry. Individual differences between cultural tourists may lead to wide variations in the manner in which they respond to communication appeals. The analysis presented in this paper is based on the tourist typology of McKercher. The dimensions of the typology are involvement and experience. The authors suggest that message perception can also be studied with the help of these dimensions. The perception processes were elaborated on the basis of Vaughn's FCB Grid model. The result of the analyses was an enriched McKercher typology that describes how different tourist types process message perception and what kind of marketing communication strategy is suitable for each type. Finally, it was illustrated with the help of the selected marketing communication material of four cultural attractions, how cultural attractions try to appeal to potential cultural tourists. The communication material mainly followed the informative strategy, but there was also potential for affective, habitual and satisfaction strategies. The authors maintain that differences in message reception should be analysed and utilised when marketing communication is planned for cultural attractions.
Testing a Conceptual Model of Cultural Tourism Development in the Post-Industrial City: A Case Study of Glasgow
Authors: Murphy Clare , Boyle Emily
Published: January 2007

This paper identifies key factors that have shaped the development of cultural tourism in post-industrial cities in the UK and presents them in a conceptual model, examining the contextual comparabilities in the transformation of many UK cities. The model is tested with qualitative data gathered through in-depth interviews with key personnel who have varying degrees of responsibility for economic, tourism and cultural development in Glasgow. This research indicates that while there are general factors that contribute to successful cultural tourism development in postindustrial cities in the UK, local contextual characteristics are influential, making the development unique to each city.
Invited Article: A unified evaluation of iterative projection algorithms for phase retrieval
Authors: Marchesini S.
Published: January 2007

Iterative projection algorithms are successfully being used as a substitute of lenses to recombine, numerically rather than optically, light scattered by illuminated objects. Images obtained computationally allow aberration-free diffraction-limited imaging and the possibility of using radiation for which no lenses exist. The challenge of this imaging technique is transferred from the lenses to the algorithms. We evaluate these new computational “instruments” developed for the phase-retrieval problem, and discuss acceleration strategies.
Geometrothermodynamics
Authors: Quevedo Hernando
Published: January 2007

We present the fundamentals of geometrothermodynamics, an approach to study the properties of thermodynamic systems in terms of differential geometric concepts. It is based, on the one hand, on the well-known contact structure of the thermodynamic phase space and, on the other hand, on the metric structure of the space of thermodynamic equilibrium states. In order to make these two structures compatible we introduce a Legendre invariant set of metrics in the phase space and demand that their pullback generates metrics on the space of equilibrium states. We show that Weinhold’s metric, which was introduced ad hoc, is not contained within this invariant set. We propose alternative metrics which allow us to redefine the concept of thermodynamic length in an invariant manner and to study phase transitions in terms of curvature singularities.
Long persistent alkali-earth silicate phosphors doped with Eu2+,Nd3+
Authors: Jia Dongdong , Jia Weiyi , Jia Yi
Published: January 2007

Phosphors of SrnMgSi2O5+n(1⩽n⩽2) singly doped with Eu2+ or doubly doped with Eu2+ and Nd3+ were prepared by using a solid state chemical reaction method. X-ray diffraction spectra revealed that the SrnMgSi2O5+n(1⩽n⩽2) compounds have the same crystal structure as Sr2MgSi2O7. The samples showed a strong blue emission at 470nm. Their excitation bands are from 250to450nm which were assigned to the 5d-4f transitions of Eu2+. Energy transfer between Eu2+ ions in inequivalent sites was found. Temperature dependence of photoluminescence was studied. A decrease of luminescence intensity and a blueshift of the emission spectra with increasing temperature were observed in both SrMgSi2O6:Eu2+ and Sr2MgSi2O7:Eu2+. Persistent afterglow was detected in the samples. The Eu2+ blue afterglow emission could be greatly enhanced by codoping trivalent rare earth ions, such as Nd3+. Thermoluminescence measurements revealed that doping with Nd3+ created a much large number of traps and hence enhanced the afterglow.
Analysis of the propagation of terahertz surface plasmon polaritons on semiconductor groove gratings
Authors: Kuttge M. , Kurz H. , Rivas J. Gómez , Sánchez-Gil J. A. , Haring Bolívar P.
Published: January 2007

We have investigated the propagation of terahertz (THz) surface plasmon polaritons (SPPs) on gratings formed by grooves structured in silicon wafers. These gratings exhibit a stop gap where SPPs are Bragg scattered. We observe a strong effect of the groove depth on the characteristics of the stop gap. To quantify the scattering strength of these structures we obtain the SPP attenuation length by measuring the transmission as a function of the number of grooves. We also determine the effective refractive index of the Bragg gratings using two different approaches: by measuring the transmittance through the gratings at different angles of incidence and from the phase of the transmitted THz pulses. The two approaches give results in good agreement.
Effects of the environmental factors on the casein micelle structure studied by cryo transmission electron microscopy and small-angle x-ray scattering/ultrasmall-angle x-ray scattering
Authors: Marchin Stéphane , Putaux Jean-Luc , Pignon Frédéric , Léonil Joëlle
Published: January 2007

Casein micelles are colloidal protein-calcium-transport complexes whose structure has not been unequivocally elucidated. This study used small-angle x-ray scattering (SAXS) and ultrasmall angle x-ray scattering (USAXS) as well as cryo transmission electron microscopy (cryo-TEM) to provide fine structural details on their structure. Cryo-TEM observations of native casein micelles fractionated by differential centrifugation showed that colloidal calcium phosphate appeared as nanoclusters with a diameter of about 2.5nm. They were uniformly distributed in a homogeneous tangled web of caseins and were primarily responsible for the intensity distribution in the SAXS profiles at the highest q vectors corresponding to the internal structure of the casein micelles. A specific demineralization of casein micelles by decreasing the pH from 6.7 to 5.2 resulted in a reduced granular aspect of the micelles observed by cryo-TEM and the existence of a characteristic point of inflection in SAXS profiles. This supports the hypothesis that the smaller substructures detected by SAXS are colloidal calcium phosphate nanoclusters rather than putative submicelles.
Comment on “Nitridation effects on Pb1 center structures at SiO2∕Si(100) interfaces” [J. Appl. Phys. 95, 4096 (2004)]
Authors: Stesmans A. , Afanas’ev V. V.
Published: January 2007

A recent X-band electron spin resonance study [Y. Miura and S. Fujieda, J. Appl. Phys. 95, 4096 (2004)] of thermal (100)Si∕SiO2 has concluded the generation of a second type of Pb1 defect as a result of postoxidation (PO) nitridation treatment in NO at 950°C. Here, in a different interpretation, it is outlined that the inference, burdened by limited signal-to-noise ratio and poor spectral resolution, may have resulted from the failure to discriminate the introduction of an isotropic weak additional signal at g∼2.0026, often observed after PO heating, readily giving way to misleading g anisotropy inference. There is no evidence for a second, N-associated variant of the familiar Pb1-type Si∕SiO2 interface defect.
On-chip separation of magnetic particles with different magnetophoretic mobilities
Authors: Liu Chengxun , Lagae Liesbet , Wirix-Speetjens Roel , Borghs Gustaaf
Published: January 2007

Recent integrations of giant magnetoresistive sensor into laboratory-on-a-chip systems enable the direct detection of biological entities such as cells coated with magnetic particles on chip. However, before detection the different biological entities need to be separated. As a model system, we investigated the separation of two types of magnetic particles (4.5 and 2μm in diameter). The motion of the particles was studied when actuated using an alternating traveling magnetic field produced by four-phase conductors on chip. Different magnetic particles migrate with different speeds in the same traveling magnetic field. By carefully choosing the frequency of the magnetic field, different magnetic particles can be separated in a microfluidic system.
Bounded version of bosonic creation and annihilation operators and their related quasicoherent states
Authors: Bagarello F.
Published: January 2007

Coherent states are usually defined as eigenstates of an unbounded operator, the so called annihilation operator. We propose here possible constructions of quasicoherent states, which turn out to be quasieigenstate of a bounded operator related to an annihilationlike operator. We use this bounded operator to construct a sort of modified harmonic oscillator and we analyze the dynamics of this oscillator from an algebraic point of view.
Improved uniformity of target illumination by combining a lens array and the technique of spectral dispersion
Authors: Jiang Xiujuan , Zhou Shenlei , Lin Zunqi
Published: January 2007

A scheme using a lens array and the technique of spectral dispersion is presented to improve target illumination uniformity in laser produced plasmas. Detailed two-dimensional simulation shows that a quasi-near-field target pattern, of steeper edges and without side lobes, is achieved with a lens array, while interference stripes inside the pattern are smoothed out by the use of the spectral dispersion technique. Moving the target slightly from the exact focal plane of the principal focusing lens can eliminate middle-scale-length intensity fluctuation further. Numerical results indicate that a well-irradiated laser spot with small nonuniformity and great energy efficiency can be obtained in this scheme.
Classification of marginally trapped Lagrangian surfaces in Lorentzian complex space forms
Authors: Chen Bang-Yen , Dillen Franki
Published: January 2007

A Lagrangian surface in a Lorentzian Kähler surface is called marginally trapped if its mean curvature vector is lightlike at each point. In this paper we classify marginally trapped Lagrangian surfaces in Lorentzian complex space forms. Our main results state that there exist three families of marginally trapped Lagrangian surfaces in C12, nine families in CP12, and nine families in CH12. Conversely, all marginally trapped Lagrangian surfaces in Lorentzian complex space forms are obtained from these 21 families.
Noncatalytic thermocouple coatings produced with chemical vapor deposition for flame temperature measurements
Authors: Bahlawane N. , Struckmeier U. , Kasper T. S. , Oßwald P.
Published: January 2007

Chemical vapor deposition (CVD) and metal-organic chemical vapor deposition (MOCVD) have been employed to develop alumina thin films in order to protect thermocouples from catalytic overheating in flames and to minimize the intrusion presented to the combustion process. Alumina films obtained with a CVD process using AlCl3 as the precursor are dense, not contaminated, and crystallize in the corundum structure, while MOCVD using Al(acetylacetone)3 allows the growth of corundum alumina with improved growth rates. These films, however, present a porous columnar structure and show some carbon contamination. Therefore, coated thermocouples using AlCl3-CVD were judged more suitable for flame temperature measurements and were tested in different fuels over a typical range of stoichiometries. Coated thermocouples exhibit satisfactory measurement reproducibility, no temporal drifts, and do not suffer from catalytic effects. Furthermore, their increased radiative heat loss (observed by infrared spectroscopy) allows temperature measurements over a wider range when compared to uncoated thermocouples. A flame with a well-known temperature profile established with laser-based techniques was used to determine the radiative heat loss correction to account for the difference between the apparent temperature measured by the coated thermocouple and the true flame temperature. The validity of the correction term was confirmed with temperature profile measurements for several flames previously studied in different laboratories with laser-based techniques.
Plasma waves in two-dimensional electron-hole system in gated graphene heterostructures
Authors: Ryzhii V. , Satou A. , Otsuji T.
Published: January 2007

Plasma waves in the two-dimensional electron-hole system in a graphene-based heterostructure controlled by a highly conducting gate are studied theoretically. The energy spectra of two-dimensional electrons and holes are assumed to be conical (neutrinolike), i.e., corresponding to their zero effective masses. Using the developed model, we calculate the spectrum of plasma waves (spatio-temporal variations of the electron and hole densities and the self-consistent electric potential). We find that the sufficiently long plasma waves exhibit a linear (soundlike) dispersion, with the wave velocity determined by the gate layer thickness, the gate voltage, and the temperature. The plasma wave velocity in graphene heterostructures can significantly exceed the plasma wave velocity in the commonly employed semiconductor gated heterostructures. The gated graphene heterostructures can be used in different voltage tunable terahertz devices which utilize the plasma waves.
Structure and properties of polycoordinate planar boron compounds
Authors: Zhao Yuan-yuan , Zhang Ming-yu , Xu Shu-hong , Sun Chia-Chung
Published: January 2007

Polycoordinate planar B compounds BXn (X=B, Al, C, N and Si; n=3–8) are optimized at B3LYP∕6-311++G (3df,p) theoretical level. For X=B, center B atom can coordinate three to eight atoms, while for X=Al, C, Si, and N, it can only coordinate three to five atoms. The natural bond orbital analysis shows that the center B atom does not violate the octet rule, though the numbers of coordinated atom even reach 8. According to molecular orbital analysis and nucleus independent chemical shift value calculation, it seems that these polycoordinate planar B compounds BXn (X=B, Al, C, N, and Si; n=3–8) hold twofold (α and π) aromatic, which play an important role in their stability and keeping all atoms in one plane.
Grain boundary impurity and porosity effects on the yield strength of nanocrystalline materials
Authors: Li James C. M.
Published: January 2007

The effect of impurities on the equilibrium and nonequilibrium boundaries is analyzed for nanocrystalline materials. Due to the purity of equilibrium grain boundaries, the strength levels off to a limiting value in the range of nano grain sizes. This limiting value increases with the total impurity content. Due to nonequilibrium grain boundaries and their effect on impurity segregation, the strength may decrease with decreasing grain size in the nanosize regime. These considerations can explain all the observed effects of grain size on strength without invoking other mechanisms for the nanosize grains. By controlling the impurity content and porosity of the grain boundaries, it is possible to synthesize ultrastrong and ductile materials.
Structural and electrical characterization of xBiScO3–(1−x)BaTiO3 thin films
Authors: Tinberg Daniel S. , Trolier-McKinstry Susan
Published: January 2007

Using a tolerance factor approach, it was predicted that xBiScO3–(1−x)BaTiO3 will have a morphotropic phase boundary that should enhance both the polarizability and permittivity, relative to the BiScO3 end member, near a composition of x=0.4. To verify this prediction, pulsed laser deposition was used to grow xBiScO3–(1−x)BaTiO3 thin films on (100) SrRuO3∕LaAlO3 and Pt-coated Si substrates. Typical growth conditions were 700°C and 100mTorr O2∕O3. The perovskite structure was found to be stable for compositions of x=0.2–0.6 in epitaxial films, with reduced stability in polycrystalline films. The temperature where the maximum permittivity occurs rises as BiScO3 is added to BaTiO3, and increasingly relaxorlike behavior is observed with increasing BiScO3 content. Room temperature permittivity values ranged from 200 to 400, with loss tangents of ∼0.1 at 10kHz. The experimental morphotropic phase boundary occurs near x=0.4. 0.4BiScO3–0.6BaTiO3 showed a broad permittivity maximum near 800 from 150–275°C. Films with x=0.4 show a coercive field of about 200kV∕cm with a modest room temperature remanent polarization near 8μC∕cm2. The films exhibit a dielectric tunability of greater than 25% at fields of ∼500kV∕cm. The combination of high polarizability and high transition temperature makes this family an interesting base composition for lead-free piezoelectrics, especially if the degree of relaxor character could be reduced.
Enhanced ferroelectric loop asymmetry of lead zirconate titanate thin films under nanoindentation
Authors: Koval V. , Reece M. J. , Bushby A. J.
Published: January 2007

The effect of mechanical stress on the local switching behavior and hysteresis properties of Pb(Zr,Ti)O3 and Mn-doped Pb(Zr,Ti)O3 ferroelectric thin films has been studied using spherical nanoindentation. A conductive WC–Co cermet indenter tip of 500μm nominal radius was employed in a modified nanoindentation system to allow the simultaneous application of driving voltage and mechanical loading, and consequently to collect the ferroelectric charge developed on thin films without a top electrode. Instrumented progressive indentation caused an enhancement of hysteresis loop deformations. The charge released versus applied voltage (Q-V) hysteresis loops gradually shifted along the voltage axis with increasing indentation force. Also, an enhanced vertical shift and hysteresis gap of the Q-V loops was observed. The parameter of horizontal loop asymmetry (δ) increased almost linearly with the force by an increment of about (0.4–0.5)×10−3∕100mN with a 50V peak drive voltage and a 50Hz sinusoidal wave form. The effect of nanoindentation on polarization reversal in thin ferroelectric films is suggested to result from a variation in residual stress state, asymmetric distribution of charged defects, and asymmetric lattice distortion produced by the inhomogeneous indentation stress field.
Electronic transport properties of multiwall carbon nanotubes/yttria-stabilized zirconia composites
Authors: Shi Sui-Lin , Liang Ji
Published: January 2007

The electrical conductivity of a composite prepared by dispersing multiwall carbon nanotubes in yttria-stabilized tetragonal zirconia matrix, and subsequent spark plasma sintering, is studied. The dc conductivity of the composites follows a scaling law of the type σ∝(p-pc)t, yielding for the percolation concentration pc=0.017 and for exponent t=3.3. The experimental result of the temperature of the conductivity suggests that for temperatures larger than 35K, conduction can be attributed to thermal fluctuation induced tunneling of the charge carriers through the insulating zirconia separating by the multiwall carbon nanotube clusters. At lower temperatures, variable range hopping conduction may be a dominant conduction mechanism.
Photolysis of allene and propyne in the 7–30eV region probed by the visible fluorescence of their fragments
Authors: Alnama Koutayba , Boyé-Péronne Séverine , Douin Stéphane , Innocenti Fabrizio , O’Reilly John , Roche Anne-Lise , Shafizadeh Niloufar , Zuin Lucia , Gauyacq Dolores
Published: January 2007

The photolysis of allene and propyne, two isomers of C3H4, has been investigated in the excitation energy range of 7–30eV using vacuum ultraviolet synchrotron radiation. The visible fluorescence excitation spectra of the excited neutral photofragments of both isomers were recorded within the same experimental conditions. Below the first ionization potential (IP), this fluorescence was too weak to be dispersed and possibly originated from C2H or CH2 radicals. Above IP, three excited photofragments have been characterized by their dispersed emission spectra: the CH radical (AΔ2-XΠ2), the C2 radical (dΠg3–aΠu3, “Swan’s bands”), and the H atom (4–2 and 3–2 Balmer lines). A detailed analysis of the integrated emission intensities allowed us to determine several apparition thresholds for these fragments, all of them being interpreted as rapid and barrierless dissociation processes on the excited potential energy surfaces. In the low energy range explored in this work, both isomers exhibit different intensity distributions in their fragment emission as a function of the photolysis energy, indicating that mutual allene↔propyne isomerization is not fully completed before dissociation occurs. The effect of isomerization on the dissociation into excited fragments is present in the whole excitation energy range albeit less important in the 7–16eV region; it gradually increases with increasing excitation energy. Above 19eV, the fragment distribution is very similar for the two isomers.
Characterization of single-crystalline PbTiO3 nanowire growth via surfactant-free hydrothermal method
Authors: Gu Haoshuang , Hu Yongming , You Jing , Hu Zhenglong , Yuan Ying , Zhang Tianjin
Published: January 2007

In this work, we present the results obtained in fabrication and characterization of single-crystalline lead titanate nanowires synthesized by surfactant-free hydrothermal method at 200°C. The as-prepared samples were characterized by means of x-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, selected-area electron diffraction, x-ray photoelectron spectroscopy (XPS), thermogravimetry and differential thermal analysis, Fourier transformation infrared spectroscopy, Raman spectroscopy, photoluminescence spectroscopy, and ultraviolet-visible spectroscopy. The results show that the products have a tetragonal perovskite structure without any other impurity phase, which are made up of a large quantity of nanowires with uniform diameters of about 12nm and lengths reaching up to 5μm, and the growth of nanowires is generally along the [001] direction. XPS result shows that the binding energy of Ti2p(3∕2) core level peak for PbTiO3 nanowires is larger than that of the corresponding ceramics and leads to the larger spin-orbit splitting (Δ[2p(3∕2)−2p(1∕2)]) for Ti2p. Raman studies show that the vibration modes of nanowires redshifted and broadened, which have shorter phonon lifetime compared to that of bulk materials. A blue light emission peaking at about 471nm (2.63eV) is observed at room temperature, oxygen vacancies are responsible for the luminescence in PbTiO3 nanowires. The band gap energy for PbTiO3 nanowires was about 4.15eV.
Effects of local Joule heating on the reduction of contact resistance between carbon nanotubes and metal electrodes
Authors: Dong Lifeng , Youkey Steven , Bush Jocelyn , Jiao Jun , Dubin Valery M. , Chebiam Ramanan V.
Published: January 2007

We report here a practical application of known local Joule heating processes to reduce the contact resistance between carbon nanotubes and metallic electrical contacts. The results presented in this study were obtained from a series of systematic Joule heating experiments on 289 single-walled carbon nanotubes (SWCNTs) and 107 multiwalled carbon nanotubes (MWCNTs). Our experimental results demonstrate that the Joule heating process decreases the contact resistances of SWCNTs and MWCNTs to 70.4% and 77.9% of their initial resistances, respectively. The I-V characteristics of metallic nanotubes become more linear and eventually become independent of the gate voltages (Vgs). For semiconducting nanotubes, the contact resistance has a similar decreasing tendency but the dependency of source-drain current (Ids) on Vgs does not change with the Joule heating process. This suggests that the reduction of the contact resistance and the decrease of the transport potential barrier are largely attributed to the thermal-energy-induced desorption of adsorbates such as water and oxygen molecules from the nanotube surface and the interface region, as well as thermal-energy-enhanced bonding between the nanotubes and electrode surfaces. In comparison to several other methods including rapid thermal annealing, e-beam lithography patterning of the top metal layer, and focused ion beam induced metal deposition of the top layer, the Joule heating process not only effectively reduces the contact resistance but also simultaneously measures the resistance and monitors the change in the transport potential barrier at the interface region.
A thickness modulation effect of HfO2 interfacial layer between double-stacked Ag nanocrystals for nonvolatile memory device applications
Authors: Ryu Seong-Wan , Choi Yang-Kyu , Mo Chan Bin , Hong Soon Hyung , Park Pan Kwi , Kang Sang-Won
Published: January 2007

This paper presents a detailed study on the effect of different thicknesses of HfO2 high-k interfacial layer between double-stacked layers of Ag nanocrystals formed by a chemical synthesis and thermal decomposition method. To confirm the formation and purity of the well-ordered Ag nanocrystals with a high density (2.7×1012cm−2), transmission electron microscopy and x-ray diffraction analysis were used. After fabricating metal-oxide-silicon structures with 2 and 6nm interfacial HfO2 and the double-stacked Ag nanocrystals, a program efficiency and retention time characteristics were investigated.
Operational degradation of organic light-emitting diodes: Mechanism and identification of chemical products
Authors: Kondakov D. Y. , Lenhart W. C. , Nichols W. F.
Published: January 2007

Despite the importance of the operational lifetime of organic light-emitting diodes (OLEDs) in practical applications, little is known about the nature of chemical reactions associated with efficiency losses during operation. To gain an insight into a chemical mechanism of operational degradation, we studied operation-induced changes in chemical compositions of fluorescent and phosphorescent OLEDs utilizing carbazole derivatives in emissive layers. We detected substantial losses of the emissive components, including the carbazole-derived host 4,4′-bis(N-carbazolyl)biphenyl (CBP) and, if present, phosphorescent dopant. Several different materials were found only in the degraded OLEDs, and some of them were isolated and identified by nuclear magnetic resonance and mass spectrometry. A similar set of products was found upon UV irradiation of CBP films. Structures of degradation products suggest that the key step in operational degradation of OLEDs is homolytic cleavage of weaker bonds, e.g., an exocyclic C–N bond in CBP, in the excited state, followed by radical addition reactions to yield stabilized π radicals. Overall, OLED operation leads to the accumulation of the neutral radical species and their reduced or oxidized forms, acting as nonradiative recombination centers and luminescence quenchers.
Spin-current shot noise in mesoscopic conductors
Authors: He Yuhui , Hou Danqiong , Han Ruqi
Published: January 2007

In this paper, we present a method to investigate the spin-current shot noise in mesoscopic conductors by using scattering matrix theory and Green’s function technique. We first derive a general expression for the spin-current noise in the zero-frequency limit and extract the shot-noise component by considering the zero-temperature limit. The expression indicates that the spin-current shot noise in one lead is caused by the transmissions to the spin-resolved states in this lead and the interferences of these transmissions. As an application, we simulate the spin-current shot noise in a spin transistor and discuss its dependence on the device parameters and the bias voltages applied to the transistor. The knowledge we gain from this study will help researchers to evaluate the spin-current shot noise in future spintronic devices.
Comparison of electronic structures of RuO2 and IrO2 nanorods investigated by x-ray absorption and scanning photoelectron microscopy
Authors: Tsai H. M. , Babu P. D. , Pao C. W. , Chiou J. W. , Jan J. C. , Krishna Kumar K. P. , Chien F. Z. , Pong W. F. , Tsai M.-H. , Chen C.-H. , Jang L. Y. , Lee J. F. , Chen R. S. , Huang Y. S. , Tsai D. S.
Published: January 2007

Electronic structures of the nanorods of RuO2 and IrO2 metallic oxides were investigated by x-ray absorption near-edge structure (XANES) and scanning photoelectron microscopy (SPEM). O K-, Ru, and Ir L3-edge XANES results reveal that hybridization between O 2p and metal t2g orbitals is weaker in IrO2 than in RuO2. The enhancement of the tip-region SPEM intensities relative to those in the sidewall regions for both RuO2 and IrO2 nanorods is found to extend over a large energy range in contrast to those of carbon nanotubes and ZnO nanorods, which are confined to deep below and near the Fermi level, respectively.
Kinetic enhancement of Raman backscatter, and electron acoustic Thomson scatter
Authors: Strozzi D. J. , Williams E. A. , Langdon A. B. , Bers A.
Published: January 2007

One-dimensional Eulerian Vlasov-Maxwell simulations are presented that show kinetic enhancement of stimulated Raman backscatter (SRBS) due to electron trapping in regimes of heavy linear Landau damping. The conventional Raman Langmuir wave is transformed into a set of beam acoustic modes [L. Yin et al., Phys. Rev. E 73, 025401 (2006)]. A low phase velocity electron acoustic wave (EAW) is seen developing from the self-consistent Raman physics. Backscatter of the pump laser off the EAW fluctuations is reported and referred to as electron acoustic Thomson scatter. This light is similar in wavelength to, although much lower in amplitude than, the reflected light between the pump and SRBS wavelengths observed in single-hot-spot experiments, and previously interpreted as stimulated electron acoustic scatter [D. S. Montgomery et al., Phys. Rev. Lett. 87, 155001 (2001)]. The EAW observed in our simulations is strongest well below the phase-matched frequency for electron acoustic scatter, and therefore the EAW is not produced by it. The beating of different beam acoustic modes is proposed as the EAW excitation mechanism, and is called beam acoustic decay. Supporting evidence for this process, including bispectral analysis, is presented. The linear electrostatic modes, found by projecting the numerical distribution function onto a Gauss-Hermite basis, include beam acoustic modes (some of which are unstable even without parametric coupling to light waves) and a strongly damped EAW similar to the observed one. This linear EAW results from non-Maxwellian features in the electron distribution, rather than nonlinearity due to electron trapping.
Optimization of electrical conductivity of LaCrO3 through doping: A combined study of molecular modeling and experiment
Authors: Ong Khuong P. , Wu Ping , Liu Li , Jiang San Ping
Published: January 2007

A combined approach of molecular modeling and experiment has been applied to optimize the electrical conductivity of LaCrO3 by screening all group IIa elements that may partially substitute La. Electronic structures of both doped and undoped LaCrO3 have been calculated and a semiconducting state for M2+-doped LaCrO3 has been demonstrated. Both theoretical and experimental results reveal that electrical conductivity of LaCrO3 is increased by doping Ca, Sr, and Ba and reaches a maximum value with Ca. The mechanism of doping behavior for all group IIa elements is discussed which may be of interest to electrode design for solid oxide fuel cells.