bluuebunny/crossref_metadata_2025 huggingface dataset:
The secret weapon in building customer strategy: the Chief Customer Officer
Authors: Bingham Curtis N.
Published: July 2009

Purpose

This paper articulates the significant value of the role of the Chief Customer Officer, namely in the CCO's ability to create and leverage customer strategy.

Design/methodology/approach

The paper offers a view of the evolution of the CCO over six years based on recently completed in‐depth interviews with more than 50 CCOs at Fortune 500, mid‐cap, and smaller companies.

Findings

The article describes the three most common reasons why CEOs hire Chief Customer Officers. The CCO role is evolving and rapidly increasing in complexity, defying simple categorization that was possible six years ago. CCOs can be classified in two dimensions according to their customer accountability and the organizational authority of their role. CCOs share three common goals: drive profitable customer behavior, create a customer‐centric culture, and driver corporate and customer strategy. Also discussed are the most critical factors that must be in place to ensure CCO success.

Research limitations/implications

While the sample size of 50 out of 300 is representative, the CCO role is evolving quickly and is adapted as necessary within each company to fit the specific organizational needs.

Originality/value

The majority of the material is new. This research begins to codify the most critical factors in the CCO role to provide structure for CEOs and Boards considering installing a CCO. CCOs should evaluate their key performance indicators to ensure they are tied to profitability so as to better justify and defend their value. Growth companies must bear in mind the need to migrate the CCO from line ownership to process ownership to properly manage complexity.
The CASA story – Lodha Group's foray into mid‐income segments
Authors: Mathur Anupriya
Published: July 2009

Purpose

The economic slowdown that hit worldwide in 2008 led to a drastic decrease in real estate sales, especially in the luxury segment. This case describes how a premium real estate company in India overcame this downturn by strategic entry into a new market segment. It discusses the role played by brand management in creating and establishing a sub‐brand in real estate.

Design/methodology/approach

The case study presents an in‐depth discussion on various aspects of the strategy adopted based on the options available for sustenance in a slowing economy, evaluation of options, market research, customer segment research, brand extension options, brand architecture and nomenclature used, marketing initiatives taken, and milestones achieved.

Findings

The case discusses the challenges that the premium real estate group was able to overcome by implementation of the adopted strategy.

Originality/value

The paper is multi‐dimensional in nature. It focuses on brand extension strategies and opportunity creation and growth in a recessionary environment, looking at a real life example of the demonstrable and significant results achieved by Lodha Group. This case can be of value to practitioners as well as academicians in the field of brand management and sub‐brand creation in real estate, specifically during an economic slowdown.
How to evaluate risk for Italian real estate funds
Authors: Giannotti Claudio , Mattarocci Gianluca
Published: July 2009

Purpose

The purpose of this paper is to define an approach useful to evaluate real estate funds on the specific characteristics of the Italian market and on the basis of international best practices.

Design/methodology/approach

The first step is to identify specific factors and portfolio construction choices that could impact directly on the variability of inflows and outflows related to real estate fund. The analysis is realised constructing standard measures of financial and downside risk and identifying a panel model that allows to explain risk measure dynamics on the basis of some investments and portfolio characteristics. Results obtained are tested with an out of sample procedure in order to evaluate the type of misclassification risk related to each model. The second step is to evaluate the impact of debt policy on the risk assumed by a real estate funds. After an analysis of debt sustainability for each real estate unit on the basis of deadlines and amount of flows related to each investment, the study proposed looks directly at the debt policy of listed real estate funds: the analysis is aimed to evaluate the relationship between leverage choice and inflows/outflows variability and the coherence between declared results and expected results for high‐leveraged funds respect to the others.

Findings

The results stemming from the use of a real estate database supplied by Beni Stabili Gestioni Società di Gestione del Risparmio showed that the portfolio's construction choice impacts strongly on the variability of results of a real estate fund. The strict linkage between characteristics of debt and type of property makes difficult to evaluate the additional risk related to debt choice but on the basis of Italian market data are possible to point out the higher difficulties for high‐leveraged funds to achieve the result communicated to the market (the so‐called target IRR).

Originality/value

The value added of the paper is to study the relevance of specific risk factors respect to portfolio's ones in the evaluation of risk exposure for a real estate portfolio and the impact of the leverage choices on the variability of inflows and outflows related to the real estate investments.
Housing supply and planning delay in the South of England
Authors: Ball Michael , Allmendinger Phil , Hughes Cathy
Published: July 2009

Purpose

There is a growing international interest in the impact of regulatory controls on the supply of housing. The UK has a particularly restrictive planning regime and a detailed and uncertain process of development control linked to it. The purpose of this paper is to present the findings of empirical research on the time taken to gain planning permission for selected recent major housing projects from a sample of local authorities in Southern England.

Design/methodology/approach

Information on a 180 major residential projects in Southern England are collected from the records of planning authorities and the data analysed for information on the extent of delay and variability in the processing time for applications.

Findings

The scale of delay found was far greater than is indicated by average official data measuring the extent to which local authorities meet planning delay targets.

Practical implications

If these results are representative of the country as a whole, they indicate that planning delay could be a major cause of the slow responsiveness of British housing supply.

Originality/value

This is the first time that planning delay in the UK has been measured in a comprehensive project‐based manner from original records.
The performance of Italian real estate mutual funds
Authors: Morri Giacomo , Lee Stephen L.
Published: July 2009

Purpose

Italian real estate mutual funds have shown enormous growth over the past few years, however, little is known about their performance. The purpose of this paper is to correct this oversight.

Design/methodology/approach

The risk‐adjusted performance, as measured by the Sharpe ratio, of 17 Italian real estate funds is valued using a number of fund characteristics and monthly data over the period 2005‐2008. Two models are constructed and ordinary least squares regressions are applied.

Findings

Active property management, the level of property‐type diversification and the way the fund is initially setup (either by subscription or by contribution) are found to be significant factors in differentiating the performance between Italian real estate funds.

Research limitations/implications

The relatively short period of time (three years) used in the empirical analysis might represent its major drawback, also considering that data cover only the upward trend of the market cycle: a further research should be addressed when a longer time series is available.

Practical implications

Results are of interest to investors and financial planners alike in revealing which factors should be considered in selecting Italian real estate funds.

Originality/value

The main contribution of the paper is to study those characteristics of Italian real estate funds which have power in explaining their performance. The area of research is well known, the sample is new.
Measuring price expectations
Authors: Taltavull Paloma , McGreal Stanley
Published: July 2009

Purpose

The purpose of this paper is to estimate the expectations component contained in the asking price of residential property, in order to assess whether expectation plays a relevant role in house price appreciation. The paper tests the role of housing characteristics and value perception on asking price.

Design/methodology/approach

The hypothesis tested in this paper is that asking price of residential properties includes an element of price expectation. The analysis utilises a valuation database of about 1,900,000 records for the Spanish housing market, each record contains information on the price that owners expect to obtain on the sale of their property and housing and neighbourhood characteristics. There are three stages to the analysis. Regression analysis is used to estimate the hedonic models and separate that part of the price arising from housing heterogeneity, a two‐stage least squares model estimates the role of expectations and a metadata approach measures those characteristics that explain the change in the explanatory power of the hedonic models over time.

Findings

The results show that the explanatory power of hedonic models change with time suggesting that the point in the market cycle modifies the perception of price. The results indicate that the theoretical variables which explain expectations account for about 8 per cent of price, with most of the unexplained element of asking prices due to reasons related with local market conditions.

Originality/value

This paper offers two original insights. First, the paper presents analysis based on asking prices and shows how this could be used as a tool to measure house price expectations. Second, the paper provides further perspectives of the Spanish housing market based on a major database of observations.
How will climate change impact on the tourism industry?
Authors: Hall Anthony J. , Clayton Anthony
Published: July 2009

Purpose

The purpose of this paper is to explore the views of industrial practitioners from Jamaica's hotel, travel and tourism industry on climate change.

Design/methodology/approach

The paper uses standard questions to explore the likely impact of climate change on tourism and the kinds of action needed by government and by industry to mitigate these impacts.

Findings

It is indicated that practitioners are aware of the growing impact of climate change on their business and the need for a co‐ordinated response.

Originality/value

The paper relates the analysis of climate issues in the Caribbean to the views and experiences of industry leaders.
Is tourism with a low impact on climate possible?
Authors: Chenoweth Jonathan
Published: July 2009

Purpose

The purpose of this paper is to examine the impact of a range of different travel and tourism options, and quantifies the carbon‐dioxide emissions resulting from international vacations, breaking down emissions categories into those resulting from transport, accommodation and recreation.

Design/methodology/approach

The paper uses summary data to review a range of possible vacation scenarios and examines their relative carbon‐dioxide emissions in order to compare the relative climatic impact of different forms of tourism and vacation options.

Findings

The paper concludes that intercontinental flights and cruise ship travel are particularly carbon‐intensive, which suggests that these two forms of tourism will be particularly vulnerable to any policy initiative to curb or price carbon emissions. Ends by considering whether climatically responsible international tourism is possible, and outlines some low‐carbon options.

Originality/value

The paper relates data on carbon emissions to the implications for tourism arising from climate change.
The impact of climate change on groundwater resources
Authors: Hendricks Franssen Harrie‐Jan
Published: July 2009

Purpose

The purpose of this paper is to indicate the limitations of the studies that address the impact of climate change on groundwater resources and to suggest an improved approach.

Design/methodology/approach

A general review, both from a groundwater hydrological and a climatological viewpoint, is given, oriented on the impact of climate change on groundwater resources.

Findings

The impact of climate change on groundwater resources is not the subject of many studies in the scientific literature. Only rarely sophisticated downscaling techniques are applied to downscale estimated global circulation model (GCM) future precipitation series for a point or region of interest. Often it is not taken into account that different climate models calculate considerably different precipitation amounts (conceptual uncertainty). The joint downscaling of the meteorological variables that govern potential evapotranspiration (ET) is never done in the context of a study that assessed the impact of climate change on groundwater resources. It is desirable that actual ET is calculated in (groundwater) hydrological models on a physical basis, i.e. by coupling the energy and water balance at the Earth's surface.

Originality/value

This review signalises a number of problems with published studies on the impact of climate change on groundwater resources. In many studies the method to downscale meteorological variables from a climate model to a hydrological model is not adequate. ET is often calculated in a strongly simplified manner and not all hydrological processes are modelled in a fully coupled fashion. More sophisticated downscaling approaches, physically based schemes to calculate ET and well‐calibrated, integrative hydrological models are needed.
Urbanization effects on temperature trends of Lahore during 1950‐2007
Authors: Sajjad S.H. , Shirazi Safdar Ali , Ahmed Khan M. , Raza Asif
Published: July 2009

Purpose

The purpose of this paper is to explore the trends of changing temperature of Lahore in Pakistan due to invigorating urbanization process since 1950‐2007.

Design/methodology/approach

This research is designed by using the numerical time series data of mean minimum temperature (MMiT), mean maximum temperature (MMxT) and mean annual temperature (MAT). The growth in urban population, area and transportation are also evaluated by using the available data. Linear regression method is applied to investigate the results of change in temperature. Three different approaches to examine the MAT are testified; first as an entire period (1950‐2007), and then by dividing the entire period into two equal phases as Phase I (1950‐1974) and Phase II (1975‐2207). MMiT and MMxT are analysed for the entire period without making any division.

Findings

The results of the paper are significantly indicating an increase in MAT and MMiT which have risen up to 0.89 and 2.51°C, respectively, while MMxT remained resolute throughout the study period. Change in MMiT is observed regular and brisk than other parameters of temperature. Increase in temperature in Phase I is observed only 0.062°C and in Phase II it is observed 0.94°C.

Research limitations/implications

This research can be further worked out by using different meteorological models to study the effects of urbanization on lower surface atmosphere and urban heat island effects in Lahore.

Originality/value

By taking into consideration these results, the town planners and government can make different strategies to mitigate the urban effects on rising temperature in Pakistan.
Seasonal rainfall variability in Guinea Savanna part of Nigeria: a GIS approach
Authors: Ayanlade Ayansina
Published: July 2009

Purpose

This paper aims to use geographical information systems kriging interpolation technique to examine and map the spatiotemporal variation in rainfall in Guinea Savanna of Nigeria.

Design/methodology/approach

Rainfall data, for the periods between 1970 and 2000, are collected from the archives of the Nigerian Meteorological Services, Oshodi Lagos. In this paper, rainfall is considered as the primary and input for crop yield. It is observed that the most important climatic element is rainfall; particularly inter‐annual variation and the spatiotemporal distribution of rainfall. Three spatial interpolation methods are chosen for this research work: inverse distance weighting method and the spline (completely regularized) as the determinist methods; and ordinary kriging as the stochastic methods. In order to analyze the interpolation quality, an evaluation by cross validation has been carried out. Ordinary kriging method was discovered suitable for this paper because it allows the sharpest interpolation rainfall data and is the most representative.

Findings

The results of the analysis show that rainfall varies both in time and space. Rainfall variability is very high in most of Northern Guinea Savanna (e.g. Yola, Minna, and Ilorin) with values of coefficient of variation (CV) between 26 and 49 percent while in Southern Guinea Savanna, the CV is very low especially, in Enugu (9 percent), and Shaki (8 percent). These anomalies (such as decline in annual rainfall, change in the peak and retreat of rainfall and false start of rainfall) are detrimental to crop germination and yield, resulting in little or no harvest at the end of the season.

Originality/value

The paper concludes that geospatial techniques are powerful tools that should be explored further for realistic analysis of the effects of seasonal variability in rainfall.
Climates of the Arabian Peninsula – past, present, future
Authors: Kotwicki Vincent , Al Sulaimani Zaher
Published: July 2009

Purpose

The purpose of this paper is to look into climate and climate change in a wider setting ranging from geological time through historical to instrumental records.

Design/methodology/approach

The authors give an overview of the past, present, and future climates and the status of water resources of the Arabian Peninsula, and describe climatic forcings that shape the current climate, and the variables that are most prone to the change of existing atmospheric conditions.

Findings

Present weather patterns of the Peninsula are governed by Hadley circulation, and modulated by El Niño – southeastern oscillation, PDO, NAO, and IOO. The process of aridification is proceeding.

Originality/value

The global assessment of the imminent climate change is streamlined into predictions that are relevant for the Arabian Peninsula. Conclusions are drawn on the need for extended research effort based in countries of the Arabian Peninsula for the optimal preparation of management actions to tackle both climate change and resulting water resources issues in the region.
Exploiting Covalency to Enhance Metal–Oxide and Oxide–Oxide Adhesion at Heterogeneous Interfaces
Authors: Jarvis Emily A. A. , Carter Emily A.
Published: July 2009

We employ first‐principles density functional calculations to explore atomic‐level interactions and predict the ideal work of adhesion at the SiO2/nickel and ZrO2/SiO2 interfaces. We find that chemical bonding at the interface serves to strengthen significantly interfaces formed with SiO2, which exhibits significant covalent bonding character, relative to those formed using more ionic oxides, such as Al2O3, in place of SiO2. The improved strength of these interfaces due to local bonding interactions may hold materials design implications for practical applications that require optimal adhesion between metal‐ceramic layered structures, including thermal barrier coatings.
Synthesis of Highly Porous Yttria‐Stabilized Zirconia by Tape‐Casting Methods
Authors: Boaro Martha , Vohs John M. , Gorte Raymond J.
Published: July 2009

Porous ceramics of Y2O3‐stabilized ZrO2 (YSZ) were prepared by tape‐casting methods using both pyrolyzable pore formers and NiO followed by acid leaching. The porosity of YSZ wafers increased in a regular manner with the mass of graphite or polymethyl methacrylate (PMMA) to between 60% and 75% porosity. SEM indicated that the shape of the pores in the final ceramic was related to the shape of the pore formers, so that the pore size and microstructure of YSZ wafers could be controlled by the choice of pore former. Dilatometry measurements showed that measurable shrinkage started at 1300 K, and a total shrinkage of 26% was observed, independent of the amount or type of pore former used. Temperature‐programmed oxidation (TPO) measurements on the green tapes demonstrated that the binders and dispersants were combusted between 550 and 750 K, that PMMA decomposed to methyl methacrylate between 500 and 700 K, and that graphite combusted above 900 K. The porosity of YSZ ceramics prepared by acid leaching of nickel from NiO–YSZ, with 50 wt% NiO, was studied as a function of NiO and YSZ particle size. Significant changes in pore dimension were found when NiO particle size was changed.
Optimization of Praseodymium‐Doped Cerium Pigment Synthesis Temperature
Authors: Masó Nahum , Beltrán Hector , Muñoz Raquel , Julián Beatriz , Carda Juan B. , Escribano Purificación , Cordoncillo Eloisa
Published: July 2009

The development of red pigments is of great interest to the ceramic industry. Pr(IV) stabilization in a CeO2 matrix yields materials with a red color. In this study, the traditional ceramic method involving solid‐state reaction was used to prepare pigments in the system Ce1−xPrxO2−δ (0.005 ≤x≤ 0.1) from mixtures of rare‐earth oxides. The chemical stability of these pigments was then determined in some industrial glazes. The glazing tests indicate that the powder samples calcined at 1200° and1300°C are unstable, whereas those calcined at 1400° and 1500°C are stable. These findings are related to the nonformation of a solid solution, to which the pigmenting power is attributed, in calcinations at temperatures below 1400°C.
Fabrication and Microstructure Characterization of Ti3SiC2 Synthesized from Ti/Si/2TiC Powders Using the Pulse Discharge Sintering (PDS) Technique
Authors: Zhang Zhe‐Feng , Sun Zheng Ming , Hashimoto Hitoshi , Abe Toshihiko
Published: July 2009

Ti/Si/2TiC powders were prepared using a mixture method (M) and a mechanical alloying (MA) method to fabricate Ti3SiC2 at 1200°–1400°C using a pulse discharge sintering (PDS) technique. The results showed that the Ti3SiC2 samples with <5 wt% TiC could be rapidly synthesized from the M powders; however, the TiC content was always >18 wt% in the MA samples. Further sintering of the M powder showed that the purity of Ti3SiC2 could be improved to >97 wt% at 1250°–1300°C, which is ∼200°–300°C lower than that of sintered Ti/Si/C and Ti/SiC/C powders using the hot isostatic pressing (HIPing) technique. The microstructure of Ti3SiC2 also could be controlled using three types of powders, i.e., fine, coarse, or duplex‐grained, within the sintering temperature range. In comparison with Ti/Si/C and Ti/SiC/C mixture powders, it has been suggested that high‐purity Ti3SiC2 could be rapidly synthesized by sintering the Ti/Si/TiC powder mixture at relatively lower temperature using the PDS technique.
Novel Fast Lithium Ion Conduction in Garnet‐Type Li5La3M2O12 (M = Nb, Ta)
Authors: Thangadurai Venkataraman , Kaack Heiko , Weppner Werner J. F.
Published: July 2009

Lithium metal oxides with the nominal composition Li5La3M2O12 (M = Nb, Ta), possessing a garnetlike structure, have been investigated with regard to their electrical properties. These compounds form a new class of solid‐state lithium ion conductors with a different crystal structure compared with all those known so far. The materials are prepared by solid‐state reaction and characterized by powder XRD and ac impedance to determine their lithium ionic conductivity. Both the niobium and tantalum members exhibit the same order of magnitude of bulk conductivity (∼10−6 S/cm at 25°C). The activation energies for ionic conductivity (<300°C) are 0.43 and 0.56 eV for Li5La3Nb2O12 and Li5La3Ta2O12, respectively, which are comparable to those of other solid lithium conductors, such as Lisicon, Li14ZnGe4O16. Among the investigated materials, the tantalum compound Li5La3Ta2O12 is stable against reaction with molten lithium. Further tailoring of the compositions by appropriate chemical substitutions and improved synthesizing methods, especially with regard to minimizing grain‐boundary resistance, are important issues in view of the potential use of the new class of compounds as electrolytes in practical lithium ion batteries.
Effect of Microstructure on Dynamic Failure Resistance of Titanium Diboride/Alumina Ceramics
Authors: Keller Andrew R. , Zhou Min
Published: July 2009

The dynamic compressive strength and microscopic failure behavior of TiB2/Al2O3ceramic composites with a range of microstructural morphologies and size scales are analyzed. A split Hopkinson pressure bar is used to achieve loading rates of the order of 400 s−1. The time‐resolved analysis of the mechanical response is conducted with a resolution of 500 ns. The dynamic compressive strengths of the materials are 4.3–5.3 GPa, indicating a dependence of strength on microstructure. Microstructures with finer phases as measured by linear intercept length have higher strength levels. The dynamic strength levels are ∼27% higher than the values of 3–4 GPa measured at quasi‐static loading rates for these materials. These strength levels are also higher than the strength levels of monolithic TiB2and Al2O3under similar dynamic conditions. A soft recovery mechanism in the experimental configuration allows the specimens to be subjected to loading under a single, well‐defined stress pulse. Scanning electron microscopy and energy dispersive spectrometry indicate that failure associated with the Al2O3phase is transgranular cleavage in all microstructures. On the other hand, failure associated with the TiB2phase is a combination of transgranular cleavage and intergranular debonding and varies with the microstructures. Quantitative image analysis shows that the measured compressive strength of the materials directly correlates with the fraction of TiB2‐rich areas on fracture surfaces. The size distribution of the fragments is quantified using digital image analysis. Comparisons of the measured distributions with the predictions of several theories suggest that the lack of accounting for microstructural characteristics contributes to the inaccuracies of the models.
Crack‐Healing Behavior of Liquid‐Phase‐Sintered Silicon Carbide Ceramics
Authors: Kim Young‐Wook , Ando Kotoji , Chu Min Cheol
Published: July 2009

Crack‐healing behavior of liquid‐phase‐sintered (LPS) SiC ceramics has been studied as functions of heat‐treatment temperature and crack size. Results showed that heat treatment in air could significantly increase the indentation strength. The heat‐treatment temperature has a profound influence on the extent of crack healing and the degree of strength recovery. The optimum heat‐treatment temperature depends on the softening temperature of an intergranular phase in each material. After heat treatment at the optimum temperature in air, the crack morphology almost entirely disappeared and the indentation strength recovered to the value of the smooth specimens at room temperature for the investigated crack sizes up to ∼200 μm. In addition, a simple heat treatment of SiC ceramics sintered with Al2O3–Y2O3–CaO at 1100°C for 1 h in air resulted in even further improvement of the strength, to a value of 1054 MPa (∼150% of the value of the unindented strength). Crack closure and rebonding of the crack wake due to oxidation of cracked surfaces were suggested as a dominant healing mechanism operating in LPS‐SiC ceramics.
Elementary Mechanisms behind the High‐Temperature Deformation Behavior of Lutetium‐Doped Silicon Nitride
Authors: Pezzotti Giuseppe , Ota Ken'ichi , Yamamoto Yoshifumi , Lin Hua‐Tay
Published: July 2009

Intergranular sliding and diffusive mechanisms behind the deformation behavior of a commercially available lutetium‐doped silicon nitride were investigated and discussed. A method of locating and separating phenomena critical for mechanical relaxation at elevated temperatures was applied; the method was based on low‐frequency forced‐vibration damping measurements. The potentiality of lutetium addition for improving the deformation resistance of silicon nitride was clearly reflected in the high‐temperature damping behavior of the investigated polycrystal. Softening of intergranular lutetium silicate phases located at multigrain junctions, which resulted in a grain‐boundary sliding peak, occurred at remarkably high temperatures (>1725 K). This phenomenon, partly overlapping diffusional flow, was followed by further damping relaxation with the melting of the lutetium silicates. Subsequent grain growth was also detected at temperatures >2100 K. Torsional creep results, collected up to 2100 K, consistently proved the presence of a “locking” effect by lutetium silicates with the sliding of silicon nitride grain boundaries below 1873 K.
Weibull Effective Volumes and Surfaces for Cylindrical Rods Loaded in Flexure
Authors: Quinn George D.
Published: July 2009

Formulas are given for the effective volumes and effective surfaces for cylindrical rods that have been loaded in flexure. Strength scaling for specimen size usually is dependent on whether the flaws are volume‐ or surface‐distributed. Flexural loadings of rods of constant diameter are an exception. The ratio of three‐point flexural strengths to four‐point flexural strengths is independent of whether the flaws are volume‐ or surface‐distributed. Rods that have been tested in flexure do not expose much material to the maximum stresses. Large rods produce strengths that are comparable to common standard‐sized rectangular bend bars for volume flaws. For surface flaws, smaller rectangular bar specimens actually have larger effective surfaces.
Microstructural Changes in Liquid‐Phase‐Sintered Silicon Carbide during Creep in an Oxidizing Environment
Authors: Schneider Judy , Biswas Koushik , Rixecker Georg , Aldinger Fritz
Published: July 2009

The knowledge of the microstructural evolution during exposure to high temperatures is important to understanding the mechanisms responsible for the creep resistance of silicon carbide (SiC) ceramics. This includes not only the phase transformation of the SiC grains, but also the phase transformations of the oxynitride grain‐boundary phases. For this study, a series of SiC specimens were prepared with varying molar ratios of AlN‐Y2O3 additives. Increased creep resistance was observed in specimens with an additive system containing a 2:3 molar ratio or 60 mol% Y2O3. A continuous oxide layer of Y2Si2O7 formed at the surface during elevated temperature testing in air. No blistering or cracking was observed in this oxide coating. Further increase of the creep resistance was achieved by a post‐sintering nitrogen anneal.
Weibull Strength Scaling for Standardized Rectangular Flexure Specimens
Authors: Quinn George D.
Published: July 2009

Formulas for the effective volumes and effective surfaces for rectangular bars loaded in flexure are reviewed. The ratio of strengths from any two configurations, such as three‐point flexural to four‐point, is independent of whether the flaws are volume‐ or surface‐distributed, if the cross‐sectional sizes are the same. Discrimination between volume‐ or surface‐distributed flaw types, based on the strength ratios, is not possible in such cases. On the other hand, conversion of strengths from one configuration to another is very easy if testing is performed in accordance with one of the current world standard test methods.
Synthesis of Niobium(V)‐Stabilized Tetragonal Zirconia Nanocrystalline Powders
Authors: Ray Jagadish C. , Panda Asit B. , Saha Chitta R. , Pramanik Panchanan
Published: July 2009

The polymer precursor method is very useful to prepare Nb5+‐stabilized nanocrystalline powders of t‐ZrO2. The precursor solution is composed of zirconium oxalate, niobium tartrate, and poly(vinyl alcohol), which help to form a network matrix to disperse the metal ions homogeneously. Nb5+ is an effective agent to stabilize t‐ZrO2, and ease of formation of the tetragonal phase increases with increasing dopant concentration. Thermal stability of t‐phase is found up to 1700°C having 15 mol% Nb5+, prepared at 600°C with particle sizes of 35 ± 5 nm.
Solid‐Solution Effects of a Small Amount of Nickel Oxide Addition on Phase Stability and Mechanical Properties of Yttria‐Stabilized Tetragonal Zirconia Polycrystals
Authors: Kondo Hiroki , Sekino Tohru , Kusunose Takafumi , Nakayama Tadachika , Yamamoto Yo , Wada Masashi , Adachi Tomohiko , Niihara Koichi
Published: July 2009

Stability and mechanical properties of the tetragonal phase were investigated for NiO‐doped yttria‐stabilized tetragonal zirconia polycrystal (Y‐TZP) systems. Only 0.3 mol% of NiO in solid solution could be added to the Y‐TZP while maintaining the tetragonal phase. Fracture toughness improved remarkably on addition of a small amount of NiO. Raman spectroscopy analysis around cracks introduced by Vickers indentation revealed that the amount of monoclinic phase transformed from tetragonal phase was increased. It was confirmed that fracture toughness improvement was due not only to increased grain size, but also to Y‐TZP destabilization by solid solution of NiO.
Silicon Nitride–Silicon Carbide Nancocomposites Fabricated by Electric‐Field‐Assisted Sintering
Authors: Wan Julin , Gasch Matthew J. , Mukherjee Amiya K.
Published: July 2009

Starting with Si‐C‐N(‐O) amorphous powders, and using the electric field assisted sintering (EFAS) technique, silicon nitride/silicon carbide nanocomposites were fabricated with yttria as an additive. It was found that the material could be sintered in a relatively short time (10 min at 1600°C) to satisfactory densities (2.96–3.09 g/cm3) using 1–8 wt% yttria. With decreasing yttria content, the ratio of SiC to Si3N4 increased, whereas the grain size decreased from ∼150 nm to as small as 38 nm. This offers an attractive way to make nano‐nanocomposites of silicon nitride and silicon carbide.
Determination of Pipe Diffusion Coefficients in Undoped and Magnesia‐Doped Sapphire (α‐Al2O3): A Study Based on Annihilation of Dislocation Dipoles
Authors: Tang Xiaohong , Lagerlöf K. Peter D. , Heuer Arthur H.
Published: July 2009

The breakup of dislocation dipoles in plastically deformed samples of undoped and 30‐ppm‐MgO‐doped sapphire (α‐Al2O3) was monitored using conventional TEM techniques. Dislocation dipoles break up into prismatic dislocation loops in a sequential process during annealing; i.e., dislocation loops are pinched off at the end of a dislocation dipole. This pinch‐off process is primarily controlled by pipe diffusion, and pipe diffusion coefficients at temperatures between 1300° and 1500°C were estimated by monitoring the kinetics of the dipole breakup process. We determined DPU= 8.1(–4.3+9.1) × 10–3 exp [–(4.5 ± 1.3eV)/kT)] m2/s for the undoped material. The pipe diffusion kinetics for the MgO‐doped crystal was determined at 1250° and 1300°C and was about 6 times higher than for undoped sapphire. Finally, climb dissociation of the dislocations constituting the perfect dipoles in sapphire is common; annihilation of one set of partials can result in the formation of faulted dipoles, which can pinch off to form faulted dislocation loops. DPU for faulted dipoles in the undoped material was determined at 1300° and 1350°C, and was about 4–10 times higher than for perfect dipoles.
Slip and Twinning in Polycrystalline Alumina (α‐Al2O3) Deformed under Hydrostatic Pressure between 600° and 1000°C
Authors: Korinek Sylvie Lartigue , Castaing Jacques
Published: July 2009

The microstructure of polycrystalline alumina deformed under hydrostatic pressure and at low temperature is investigated by transmission electron microscopy. Deformation occurs mainly by prism plane slip and rhombohedral twinning. Introduction of hydrogen leads to a significant decrease in the yield stress. In large grain size alumina deformed with hydrogen, accommodation of twinning involves dislocation reactions in the twin boundary and in the grains rather than by cracking. Prism plane dislocations decompose into basal dislocations by cross slip probably due to a decrease of Peierls stress for basal slip in the presence of hydrogen.
Structure and Chemistry of Symmetrical Tilt Grain Boundaries in α‐Al2O3: II, Bicrystals with Y at the Interface
Authors: Gemming Thomas , Nufer Stefan , Kurtz Wolfgang , Rühle Manfred
Published: July 2009

Symmetrical tilt grain boundaries (STGBs) on the (10¯10), (¯2112), and (01¯18) planes in α‐Al2O3 have been investigated for their behavior with respect to yttrium doping by performing a combined study of high‐resolution transmission electron microscopy and spatially resolved energy dispersive X‐ray analysis. Bicrystals have been produced by diffusion bonding under ultrahigh vacuum; yttrium was introduced before the bonding process. The prismatic twin has a bulklike grain boundary (GB) structure and does not accommodate any yttrium at the GB. The yttrium at the Σ17 (¯2112) GB and the Σ37 (01¯18) GB changes the GB structure and the content of other impurities.
Dislocation Structures of Low‐Angle and Near‐Σ3 Grain Boundaries in Alumina Bicrystals
Authors: Ikuhara Yuichi , Nishimura Hitoshi , Nakamura Atsutomo , Matsunaga Katsuvuki , Yamamoto Takahisa , Lagerlöf K. Peter D.
Published: July 2009

Alumina bicrystals with low‐angle and near‐Σ3 <0001> tilt grain boundaries were fabricated using diffusion bonding to study the dislocation structures in alumina grain boundaries. The resulting grain‐boundary structures were investigated using high‐resolution transmission electron microscopy, and the grain‐boundary energies were analyzed using theoretical calculations. It was found that partial dislocations with Burgers vectors of the type return ⅓<10[Onemacr]0> were periodically located in the boundaries and that a stacking fault between pairs of partials was formed in such boundaries. The length of the stacking fault decreased with increased misorientation angles, which was reasonably predicted by the theoretical calculation. In the case of a near‐Σ3 grain boundary, an array of displacement shift complete dislocations with the Burgers vector of return ⅓<1[Onemacr]00> was periodically formed along the boundaries. These boundaries did not have stacking faults. The spacing between the dislocations decreased with increased deviation angle from the exact‐Σ3 boundary with the tilt angle of 60°.
Singular Grain Boundaries in Alumina and Their Roughening Transition
Authors: Park Chan Woo , Yoon Duk Yong , Blendell John E. , Handwerker Carol A.
Published: July 2009

The shapes and structures of grain boundaries formed between the basal (0001) surface of large alumina grains and randomly oriented small alumina grains are shown to depend on the additions of SiO2, CaO, and MgO. If a sapphire crystal is sintered at 1620°C in contact with high‐purity alumina powder, the grain boundaries formed between the (0001) sapphire surface and the small alumina grains are curved and do not show any hill‐and‐valley structure when observed under transmission electron microscopy (TEM). These observations indicate that the grain boundaries are atomically rough. When 100 ppm (by mole) of SiO2 and 50 ppm of CaO are added, the (0001) surfaces of the single crystal and the elongated abnormal grains form flat grain boundaries with most of the fine matrix grains as observed at all scales including high‐resolution TEM. These grain boundaries, which maintain their flat shape even at the triple junctions, are possible if and only if they are singular corresponding to cusps in the polar plots of the grain boundary energy as a function of the grain boundary normal. When MgO is added to the specimen containing SiO2 and CaO, the flat (0001) grain boundaries become curved at all scales of observation, indicating that they are atomically rough. The grain boundaries between small matrix grains also become defaceted and hence atomically rough.
Structure of Sapphire Bicrystal Boundaries Produced by Liquid‐Phase Sintering
Authors: Hockey Bernard J. , Wiederhorn Sheldon M. , Blendell John E. , Lee Jong‐Sook , Kang Myung‐Koo
Published: July 2009

The structure and composition of sapphire bicrystal boundaries produced by liquid‐phase sintering depended on the crystallographic misorientation of the crystals across the boundary and on the orientation of the boundary. Basal twist boundaries of 15° or 30° were not wetted by glass, but contained significant amounts of Ca and Si at the boundary. For tilt boundaries of 7° or 12°, the glass wetted segments of boundaries that contained the basal plane of either crystal. Boundary segments with orientations of 40° or more from the basal plane, however, were dewetted (i.e., “dry”). Boundary segments oriented less than ∼40° from the basal orientation were partially wetted, consisting of segments of wetted and dry grain boundaries. For the 12° tilt boundary, Ca and Si could be detected on portions of the boundary that contained no glass. For bicrystal boundaries having tilts of ≤4°, dewetting occurred for all observed boundary orientations. Basal‐oriented segments in these small angle tilt boundaries contained noticeable concentrations of adsorbed Ca and Si, while nonbasal segments were apparently free of Ca and Si. Most results could be explained based on a combined Wulff plot construction, which predicts partially wetted grain boundaries and “missing” angles for unwetted grain boundaries. Results that could not be explained by the construction included growth step ledges bounded by nonequilibrium facet planes.
Alternative Explanation for the Role of Magnesia in the Sintering of Alumina Containing Small Amounts of a Liquid Phase
Authors: Kim Byung‐Ki , Hong Seong‐Hyeon , Lee Sang‐Ho , Kim Doh‐Yeon , Hwang Nong Moon
Published: July 2009

The microstructural evolution during sintering of Al2O3 was investigated to determine the role of MgO additive, particularly when its concentration is very low (<200 ppm). Compared with specimens without MgO, a few Al2O3 grains were observed to grow enormously after the addition of 50 or 100 ppm MgO. When MgO content was increased to 200 ppm, on the other hand, the overall grain growth process was accelerated and many growing grains impinged on each other. In this case, therefore, a fine and unimodal grained microstructure was obtained. Sintering of Al2O3 in a MgO atmosphere further supported the promotion of grain growth by MgO. It is proposed that MgO promotes the grain growth of Al2O3 either by lowering the edge energy or by roughening the interface structure.
Abnormal Grain Growth of Alumina: CaO Effect
Authors: Jung Joonchul , Baik Sunggi
Published: July 2009

The critical concentration of Ca required for the onset of abnormal grain growth in alumina was determined by controlled doping of Ca in ultrapure alumina (>99.999%), by sintering under clean contamination‐free conditions, and by microstructural characterization. As in the case of Si, the excess concentration of Ca beyond its solubility limit was inversely related to the average grain size at the moment of first appearance of abnormal grains, which corresponds to the moment of sufficient enrichment of Ca in grain boundaries to form stable intergranular liquid films. However, the critical concentration of Ca was found to be in the range of only a few tens of ppm, which is lower than that of Si by almost 2 orders of magnitude. The equivalent silica concentration to form such a stable intergranular calcium aluminate glass film and its minimum thickness were estimated from the inverse relationship with the assumption that the glass composition is close to calcium hexaluminate.
Alumina Grown during Deposition of Thermal Barrier Coatings on NiCrAlY
Authors: Levi Carlos G. , Sommer Eric , Terry Scott G. , Catanoiu Amalia , Rühle Manfred
Published: July 2009

The microstructure of Al2O3 formed by oxidation of a model NiCrAlY alloy during electron‐beam physical vapor deposition of ZrO2–7.6 mol% YO1.5 is examined and compared with that formed on the bare substrate. The growth rate, morphology, and chemical composition of the oxide vary among the different constituents of the alloy surface and are further influenced by the O2 partial pressure and the physical presence of the thermal barrier coating (TBC) layer. These differences, however, are largely limited to the outer oxide layer. The interplay between the TBC and the growing oxide leads to the formation of a fine‐grain Al2O3–ZrO2“mixed zone” within the thermally grown oxide. A mechanism is outlined to explain this behavior, based on the dissolution of ZrO2 in a transient Al2O3 structure growing by outward diffusion of Al, and its subsequent reprecipitation when the metastable phase transforms to the stable α‐Al2O3 form.
Adhesion of Copper and Alumina from First Principles
Authors: Wang Xiao‐Gang , Smith John R. , Scheffler Matthias
Published: July 2009

Structures and energetics of various, plausible realizations of the Al2O3(0001)/Cu(111) interface have been studied by density‐functional theory. The oxygen‐terminated interface is found to be relatively strong with a work of separation (Wsep) of 7.03 J/m2. For hydrogen‐rich (e.g., moist) conditions, we have determined that the interface accommodates about 1/3 of a monolayer of hydrogen. This lowers Wsep to 4.72 J/m2, which is, however, greater than the corresponding value for bulk copper, which implies that fracture in such a system occurs in the copper region, consistent with fracture toughness experiments. We also have studied the initial stages of copper and aluminum growth on the hydrogen‐stabilized oxygen‐terminated Al2O3(0001) surface. Although a monolayer of aluminum already completely dissociates the interfacial O‐H group, a monolayer of copper leaves it intact. If, for a thick copper film, such a full hydrogen layer were maintained, the resulting metastable interface would be very weak, with Wsep= 0.63 J/m2.
Titanium Diboride–Tungsten Diboride Solid Solutions Formed by Induction‐Field‐Activated Combustion Synthesis
Authors: Shibuya Masachika , Kawata Makoto , Ohyanagi Manshi , Munir Zuhair A.
Published: July 2009

Solid solutions of titanium diboride–tungsten diboride (TiB2–WB2) were synthesized by induction‐field‐activated combustion synthesis (IFACS) using elemental reactants. In sharp contrast to conventional methods, solid solutions could be formed by the IFACS method within a very short time, ∼2 min. Solutions with compositions ranging from 40–60 mol% WB2 were synthesized with a stoichiometric ratio (Ti + W)/B =½; however, samples with excess boron were also made to counter the loss of boron by evaporation. The dependence of the lattice constants of the resulting solid solutions on composition was determined. The “a” parameter decreased only slightly with an increase in the WB2 content, whereas the “c” parameter exhibited a significant decrease over the range 40–60 mol% WB2. Solid‐solution powders formed by the IFACS method were subsequently sintered in a spark plasma sintering (SPS) apparatus. After 10 min at 1800°C, the samples densified to relative density 86%. XRD analysis showed the presence of only the solid‐solution phase.