Search query: perovskite nanocrystal rare earth

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abstract: We report a simple, eco friendly facile wet chemical route for the synthesis of pristine and rare earth metal co doped (Er/Yb, 10/90, 15/85, 20/80) nano crystalline, strontium stannate (SrSnO3) whiskers. It is n type wide bandgap ~4.1 eV) orthorhombic perovskite semiconductor at room temperature, and reveals increase in band gap with the increase in Er/Yb content (from 4.10 to 4.23, 4.30 to 4.39 eV) The samples exhibited strong emission around 365 nm following band edge excitation by the wavelength of 290 nm. Further, strong up conversion emission was observed in visible range at the excitation of wavelength 980 nm. The resistivity values were found to decrease with increase in the dopants Er/Yb concentration due to enhancement of charge carriers.
author_names: Ashok Kumar

Vikas Sahrawat

Astakala Anil Kumar

Shashank Priya
title: Up Conversion in Perovskite Strontium Stannate Nanocrystal Whiskers
venue: Transactions of the Indian Institute of Metals
year: 2017

abstract: Much effort has gone into realizing laser cooling with solids over the last two decades. Multiple attempts have been made with systems that include rare earth doped glasses, GaAs heterostructures, CdS nanobelts and hybrid perovskite nanoplatelets. Here we suggest that CsPbBr3 perovskite nanocrystals may eventually lead to verifiable demonstrations of condensed phase laser cooling. The highest emission quantum yield we have realized in CsPbBr3 nanocrystal ensembles is 99.9% at room temperature. This value lies above the critical quantum yield for CsPbBr3, needed to realize laser cooling. We also find that associated CsPbBr3 nanocrystal emission up conversion efficiencies are large and are 75% and 32% for laser detuning energies of 24 meV and 105 meV.
author_names: Shubin Zhang

Maksym Zhukovskyi

Boldizsar Janko

Masaru Kuno
title: Evaluation of CsPbBr3 nanocrystals for laser cooling
venue: OPTO
year: 2019

abstract: As star material, perovskites have been widely used in the fields of optics, photovoltaics, electronics, magnetics, catalysis, sensing, etc. However, some inherent shortcomings, such as low efficiency (power conversion efficiency, external quantum efficiency, etc. and poor stability (against water, oxygen, ultraviolet light, etc. limit their practical applications. Downsizing the materials into nanostructures and incorporating rare earth (RE) ions are effective means to improve their properties and broaden their applications. This review will systematically summarize the key points in the design, synthesis, property improvements and application expansion of RE containing (including both RE based and RE doped) halide and oxide perovskite nanomaterials (PNMs) The critical factors of incorporating RE elements into different perovskite structures and the rational design of functional materials will be discussed in detail. The advantages and disadvantages of different synthesis methods for PNMs will be reviewed. This paper will also summarize some practical experiences in selecting suitable RE elements and designing multi functional materials according to the mechanisms and principles of REs promoting the properties of perovskites. At the end of this review, we will provide an outlook on the opportunities and challenges of RE containing PNMs in various fields.
author_names: Zhichao Zeng

Yueshan Xu

Zheshan Zhang

Zhansheng Gao

Meng Luo

Zongyou Yin

Chao Zhang

Jun Xu

Bolong Huang

Feng Luo

Yaping Du

Chunhua Yan
title: Rare earth containing perovskite nanomaterials: design, synthesis, properties and applications.
venue: Chemical Society reviews
year: 2020

abstract: The invention relates to a high heat stability nanocrystal rare earth permanent magnet material, belonging to the technical field of magnetic materials. The basic expression of the permanent magnet material is RxFe[100 x y z]ByMz, wherein R is one or more of light rare earth elements neodymium, praseodymium and cerium, Fe is iron, B is boron, and M is one or more of zirconium and hafnium; and x, y and z represent atomic percents, 12<=x<=14.9, 5<=y<=10, and 0.1<=z<=4. The invention also relates to a preparation method of the rare earth permanent magnet material. The high heat stability nanocrystal rare earth permanent magnet material is free of the heavy rare earth element Dy or Tb, has low total rare earth content, and is free of the element Co; and the high heat stability nanocrystal rare earth permanent magnet material has the advantages of low coercivity temperature coefficient, high heat stability and fine and uniform grain size. The preparation process does not need annealing technique treatment, has the advantages of simple technique and lower cost, and thus, is suitable for large scale production.
title: High heat stability nanocrystal rare earth permanent magnet material and preparation method thereof
year: 2016

abstract: Abstract We presented the structural, magnetic, and magnetocaloric data for perovskite TmFeO3. XRD revealed distorted orthorhombic structure (Pbnm) for TmFeO3. Spin reorientation transition was confirmed through magnetic susceptibility. DSM(max) is 13.72 Jkg 1 K 1 at the temperature of 85 K under DH 6 T, with the RCP value of 676 J/kg. DSM(max) and RCP values were increased with the applied field, possibly due to the d f exchange interactions. The magnetic hysteresis cycles are established for different values of temperatures. These properties make it a potential candidate used for magnetic refrigerants. For magnetic refrigeration application, very large refrigeration capacity is also required along with large entropy change value.
author_names: Poorva Sharma

Rachid Masrour

A Jabar

Jiyu Fan

Ashwini Kumar

Langsheng Ling

Chunlan Ma

Caixia Wang

Hao Yang
title: Structural and magnetocaloric properties of rare earth orthoferrite perovskite: TmFeO3
year: 2020

abstract: Perovskite manganites exhibit a broad range of structural, electronic, and magnetic properties, which are widely investigated since the discovery of the colossal magnetoresistance effect in 1994. As compared to the parent perovskite manganite oxides, rare earth doped perovskite manganite oxides with a chemical composition of LnxA1 xMnO3 (where Ln represents rare earth metal elements such as La, Pr, Nd, A is divalent alkaline earth metal elements such as Ca, Sr, Ba) exhibit much diverse electrical properties due to that the rare earth doping leads to a change of valence states of manganese which plays a core role in the transport properties. There is not only the technological importance but also the need to understand the fundamental mechanisms behind the unusual magnetic and transport properties that attract enormous attention. Nowadays, with the rapid development of electronic devices toward integration and miniaturization, the feature sizes of the microelectronic devices based on rare earth doped perovskite manganite are down scaled into nanoscale dimensions. At nanoscale, various finite size effects in rare earth doped perovskite manganite oxide nanostructures will lead to more interesting novel properties of this system. In recent years, much progress has been achieved on the rare earth doped perovskite manganite oxide nanostructures after considerable experimental and theoretical efforts. This paper gives an overview of the state of art in the studies on the fabrication, structural characterization, physical properties, and functional applications of rare earth doped perovskite manganite oxide nanostructures. Our review first starts with the short introduction of the research histories and the remarkable discoveries in the rare earth doped perovskite manganites. In the second part, different methods for fabricating rare earth doped perovskite manganite oxide nanostructures are summarized. Next, structural characterization and multifunctional properties of the rare earth doped perovskite manganite oxide nanostructures are in depth reviewed. In the following, potential applications of rare earth doped perovskite manganite oxide nanostructures in the fields of magnetic memory devices and magnetic sensors, spintronic devices, solid oxide fuel cells, magnetic refrigeration, biomedicine, and catalysts are highlighted. Finally, this review concludes with some perspectives and challenges for the future researches of rare earth doped perovskite manganite oxide nanostructures.
author_names: Weiren Xia

Zhipeng Pei

Kai Leng

Xinhua Zhu
title: Research Progress in Rare Earth Doped Perovskite Manganite Oxide Nanostructures
venue: Nanoscale Research Letters
year: 2020

abstract: Piezoelectric materials are technologically important, and the most used are perovskite ferroelectrics. In recent years, more and more emerging areas have put forward new requirements for piezoelectric materials, such as light weight, low acoustic impedance, good flexibility and biocompatibility. In this context, hybrid organic inorganic perovskite ferroelectrics have emerged as promising supplements, because they combine attractive features of inorganic and organic materials. Among them, hybrid double metal perovskites have recently been found to exhibit excellent ferroelectricity. However, their potential as piezoelectric materials hasn't been exploited. Here, we describe large piezoelectric response in hybrid rare earth double perovskite relaxor ferroelectrics (RM3HQ)2RbLa(NO3)6 and (RM3HQ)2NH4La(NO3)6 (RM3HQ R N methyl 3 hydroxylquinuclidinium) They are of the simultaneously ferroelectric and ferroelastic crystals with the R3 ferroelectric phase and P213 paraelectric phase. We found that ferroelectric polar micro domains and paraelectric non polar regions coexist in a wide temperature range through variable temperature piezoresponse force microscopy (PFM) images. The two phase coexist ence reveals low energy barriers of transitions between the two phases and between the polar micro domains with different polarization directions. These lead to the easy polarization rotation of the polar micro domains upon applying a stress, and accordingly, the large piezoelectric response up to 106 pC N 1 for (RM3HQ)2RbLa(NO3)6. This finding represents a significant step toward novel applications of piezoelectric materials based on lead free hybrid perovskites.
author_names: Chao Shi

JiaJun Ma

Jiaying Jiang

Miao-Miao Hua

Qi Xu

Hui Yu

Yiren Zhang

Heng-Yun Ye
title: Large Piezoelectric Response in Hybrid Rare Earth Double Perovskite Relaxor Ferroelectrics.
venue: Journal of the American Chemical Society
year: 2020

abstract: Abstract Here, we report a comparative study of rare earth doped La0.6R0.1Ca0.3MnO3 (R La, Nd, Sm, Gd, and Dy) samples synthesized by sol gel Pechini process. All the compounds are single phased and crystallize in Pbnm space group with orthorhombic symmetry. Temperature dependent magnetization measurements revealed that all our compounds exhibit a paramagnetic (PM) ferromagnetic (FM) transition with decrease in both ordering temperature TC and the freezing temperature TF with decrease in ionic radii of lanthanide ions. The compounds display metal semiconductor transition and the temperatures (TMS) obtained from the electrical resistivity measurements are consistently higher than those of the Curie temperatures TC. The transport properties are dominated by the Variable range hopping (VRH) model above TMS, showing an increase in characteristic VRH temperature with decreasing size of rare earth ion. The estimated hopping distance (RH) in all the samples is close to nearest neighbor Mn O Mn distance ~5 A) in the ab plane.
author_names: Nisha Choudhary

Mukesh kumar Verma

Narayan Dutt Sharma

Suman Kumar Sharma

Devinder Singh
title: Correlation between magnetic and transport properties of rare earth doped perovskite manganites La0.6R0.1Ca0.3MnO3 (R La, Nd, Sm, Gd, and Dy) synthesized by Pechini process
year: 2020

abstract: Perovskite graphene nanocomposites of rare earth LaFeO3 rGO and LaFeO3 nanoparticles are synthesized and characterized. The preparation was done by citrate sol gel method. The structural characterization has been performed using XRD and FT IR. Scanning electron microscope (SEM) and atomic force microscope (AFM) were used to analyze the morphology of the prepared nanocomposite. Vibrating sample magnetometer (VSM) was used to study the magnetic properties of the investigated samples. Introducing graphene to the structure results increase in MS. Also, the optical and thermal properties have been measured and discussed, and the effect of graphene is observed where it decreases the band gap than reported for pure LaFeO3 nanoparticles.
author_names: Seham K Abdel-Aal

Ahmed S Abdel-Rahman
title: Graphene influence on the structure, magnetic, and optical properties of rare earth perovskite
venue: Journal of Nanoparticle Research
year: 2020

abstract: High entropy oxides (HEO) are a recently introduced class of oxide materials, which are characterized by a large number of elements (i.e. five or more) sharing one lattice site which crystallize in a single phase structure. One complex example of the rather young HEO family are the rare earth transition metal perovskite high entropy oxides. In this comprehensive study, we provide an overview over the magnetic properties of three perovskite type high entropy oxides. The compounds have a rare earth site which is occupied by five different rare earth elements, while the transition metal site is occupied by a single transition metal. In this way a comparison to the parent binary oxides, namely the orthocobaltites, chromites and ferrites is possible. X ray absorption near edge spectroscopy (XANES) magnetometry and M\"ossbauer spectroscopy are employed to characterize these complex materials. In general, we find surprising similarities to the magnetic properties of the binary oxides, despite the chemical disorder on the rare earth site. However distinct differences and interesting magnetic properties are also observed such as noncollinearity, spin reorientation transitions as well as large coercive fields of up to 2\,T at ambient temperature. Both the chemical disorder on the RE A site, and the nature of the TM on the B site play an important role in the physical properties of these high entropy oxides.
author_names: Ralf Witte

Abhishek Sarkar

Leonardo Velasco

Robert Kruk

Richard A Brand

B Eggert

Katharina Ollefs

Eugen Weschke

Heiko Wende

Horst Hahn
title: Magnetic properties of rare earth and transition metal based perovskite type high entropy oxides
year: 2020