Ferro-electric and magnetic properties in Bi5Ti3FeO15 films by Mn-doping

ABSTRACTIn this paper, the effect of substrate on the domain structure growth and electrical and magnetic properties of epitaxial Mn-doped Zn0.8Mn0.15O (ZnMnO) thin films has been investigated. Epitaxial thin films of ZnMnO dilute magnetic semiconductors (DMS) were grown on various substrates such as single crystal sapphire, single crystal silicon, and quartz substrates using Pulsed Laser Deposition (PLD) technique . Structural, surface, magnetic, and optical properties have been observed on these films using X-Ray diffraction (XRD), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), and Raman spectroscopy. X-Ray Diffraction shows that films are highly epitaxial and c-axis oriented with some induced strain. AFM images show that film surface is smooth with RMS roughness of the order of 1-2 nm over 5*5sq.micron. Magnetic characteristic properties such as carrier concentration, mobility, and temperature dependent resistivity were also investigated. Carrier concentration decreases and mobility increases for both the films on silicon and quartz substrates when compared to film on sapphire.

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Spin Polarons at High Temperatures in Undoped Lanthanum Manganites

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.168-169.473 ◽

2010 ◽

Vol 168-169 ◽

pp. 473-476

Author(s):

T.I. Arbuzova ◽

Sergey V. Naumov ◽

Natalia V. Kostromitina

Keyword(s):

Magnetic Properties ◽

Curie Temperature ◽

Cell Volume ◽

High Temperatures ◽

Unit Cell Volume ◽

Paramagnetic State ◽

Unit Cell ◽

Temperature Range ◽

Lanthanum Manganites ◽

Spin Polarons

Magnetic properties of undoped samples of lanthanum manganites in the temperature range 77-650K are reported. The ferromagnetic Curie temperature increases when the unit-cell volume decreases and the number of cation defects increases. Uncorrelated polarons and noninteracting moments of Mn ions are present in the region TC < T < 440K. Above 2TC < 440 K < T, the nonstoihiometric LaMnO3 compound passes into the homogeneous paramagnetic state.

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In situ XRPD study of the ambient-pressure synthesis of nonstoichiometric Ag3O from Ag–Ag2O thin films: Phase abundance, unit-cell parameters, and c/a as a function of temperature and time

Powder Diffraction ◽

10.1017/s0885715620000561 ◽

2020 ◽

Vol 35 (4) ◽

pp. 247-261

Author(s):

Paul J. Schields ◽

Nicholas Dunwoody ◽

David Field ◽

Zachary Wilson

Keyword(s):

Thin Films ◽

Cell Volume ◽

Room Temperature ◽

Unit Cell Volume ◽

Ambient Pressure ◽

Thermal Reaction ◽

Unit Cell ◽

Unit Cell Parameters ◽

Cell Parameters

Ag3O was synthesized by jet-milling magnetron-sputtered Ag–Ag2O thin films. Heating the jet-milled powders in air and N2 from 40 to 148 °C at ambient pressure produced Ag3O-rich powders. The phase composition and unit-cell parameters of the jet-milled powders were measured as a function of temperature with in situ X-ray powder diffraction experiments from −186 to 293 °C. Ag3O was also produced by ball milling and sonicating jet-milled films at ambient conditions. The phase composition, unit-cell parameters, and thermal-reaction rates indicate nonstoichiometric Ag3O was produced from the reaction of metastable, nonstoichiometric Ag2O (cuprite structure) and ccp Ag. The thermal expansion of Ag3O is anisotropic; below 25 °C, the a-axis expansion is about twice the c-axis expansion resulting in a negative slope of c/a(T). The reversal of the sign of c/a(T) near 25 °C is dramatic. The thermal reaction is arrested when the temperature is rapidly increased from ambient to 130 °C. Ag3O is metastable and decreases its unit-cell volume during kinetic decomposition to Ag when heated above ambient temperature in air and nitrogen. The relative volume expansion of Ag3O is about 80% less than Ag at room temperature and below. The suite of nonstoichiometric Ag3O produced by heating displays a linear relation between c/a and unit-cell volume at room temperature. The c/a and unit-cell volume of a hydrothermally grown Ag3O single crystal reported in a published structure determination was the Ag-rich, low-volume end member of the linear series. The c/a and unit-cell volume are sensitive indicators of the oxygen content and state of disorder.

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Influence of Co Doping on Structural and Magnetic Properties of Fe2P

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.171.93 ◽

2011 ◽

Vol 171 ◽

pp. 93-106

Author(s):

Sudhish Kumar ◽

Anjali Krishnamurthy ◽

Bipin K. Srivastava

Keyword(s):

Magnetic Properties ◽

Cell Volume ◽

Unit Cell Volume ◽

Structural Parameters ◽

Hexagonal Phase ◽

Magnetic Transition ◽

Unit Cell ◽

Co Substitution ◽

Co Doping ◽

Co Concentration

The aim of this article is to provide an overview on the effect of Co doping for Fe in Fe2P on the lattice parameters, magnetic transition point, saturation magnetic moment, paramagnetic Curie point and paramagnetic moment. Five alloys in the series (Fe1-xCox)2P (x= 0.03, 0.10, 0.30, 0.50, 0.70) were synthesized and investigated using X-ray diffraction, magnetization and paramagnetic susceptibility measurements. Alloys with x=0.03 and 0.10 crystallize in Fe2P type hexagonal structure while those for x= 0.30, 0.50, 0.70 crystallize in Co2P type orthorhombic structure. In the hexagonal phase, the substitution of Co for Fe leads to a very little enhancement in the unit cell volume but in the orthorhombic phase the increase in Co concentration leads to monotonic decrease in the unit cell volume. All the five alloys are ferromagnetically ordered and  display nonlinearity in the -1-T curves above Tc. Interestingly, the compounds for x= 0.10, 0.30 and 0.50 shows a sharp first order type ferromagnetic to paramagnetic phase transition. The paramagnetic Curie temperature (θP) increases up to x=0.50. The saturation magnetizations and paramagnetic moments monotonically decrease with the increase in the Co concentration. Both Ni and Co substitution for Fe in Fe2P are known to strengthen the ferromagnetic ordering, however, the effect of Co substitution has stronger influence on the structural parameters and magnetic properties than the Ni. The observed nonlinearity in the -1-T curves above Tc and the Rhodes- Wohlfarth ratio (μP/μs) greater than one, gives a clear evidence of presence of large magnetic correlations far above Tc and itinerant magnetism in these compounds.

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Derivation of unit cell volume, and lattice parameter of cubic high entropy alloys from volume size factors

Intermetallics ◽

10.1016/j.intermet.2021.107299 ◽

2021 ◽

Vol 137 ◽

pp. 107299

Author(s):

J. Coreño Alonso ◽

O. Coreño Alonso

Keyword(s):

Cell Volume ◽

Unit Cell Volume ◽

Lattice Parameter ◽

Unit Cell ◽

High Entropy Alloys ◽

High Entropy ◽

Volume Size

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Allanite at high temperature: effect of REE on the thermal behaviour of epidote-group minerals

Physics and Chemistry of Minerals ◽

10.1007/s00269-021-01154-6 ◽

2021 ◽

Vol 48 (9) ◽

Author(s):

G. Diego Gatta ◽

Francesco Pagliaro ◽

Paolo Lotti ◽

Alessandro Guastoni ◽

Laura Cañadillas-Delgado ◽

...

Keyword(s):

Cell Volume ◽

Thermal Behaviour ◽

Unit Cell Volume ◽

Unit Cell ◽

Atomic Scale ◽

Elastic Behaviour ◽

Positive Trend ◽

Cell Parameters ◽

Thermal Anisotropy ◽

Different Temperatures

AbstractThe thermal behaviour of a natural allanite-(Ce) has been investigated up to 1073 K (at room pressure) by means of in situ synchrotron powder X-ray diffraction and single-crystal neutron diffraction. Allanite preserves its crystallinity up to 1073 K. However, up to 700 K, the thermal behaviour along the three principal crystallographic axes, of the monoclinic β angle and of the unit-cell volume follow monotonically increasing trends, which are almost linear. At T > 700–800 K, a drastic change takes place: an inversion of the trend is observed along the a and b axes (more pronounced along b) and for the monoclinic β angle; in contrast, an anomalous increase of the expansion is observed along the c axis, which controls the positive trend experienced by the unit-cell volume at T > 700–800 K. Data collected back to room T, after the HT experiments, show unit-cell parameters significantly different with respect to those previously measured at 293 K: allanite responds with an ideal elastic behaviour up to 700 K, and at T > 700–800 K its behaviour deviates from the elasticity field. The thermo-elastic behaviour up to 700 K was modelled with a modified Holland–Powell EoS; for the unit-cell volume, we obtained the following parameters: VT0 = 467.33(6) Å3 and αT0(V) = 2.8(3) × 10–5 K−1. The thermal anisotropy, derived on the basis of the axial expansion along the three main crystallographic directions, is the following: αT0(a):αT0(b):αT0(c) = 1.08:1:1.36. The T-induced mechanisms, at the atomic scale, are described on the basis of the neutron structure refinements at different temperatures. Evidence of dehydroxylation effect at T ≥ 848 K are reported. A comparison between the thermal behaviour of allanite, epidote and clinozoisite is carried out.

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Study of Structural, Magnetic, and Mossbauer Properties of Dy2Fe16Ga1−xNbx (0.0 ≤ x ≤ 1.0) Prepared via Arc Melting Process

Magnetochemistry ◽

10.3390/magnetochemistry7030042 ◽

2021 ◽

Vol 7 (3) ◽

pp. 42

Author(s):

Jiba N. Dahal ◽

Kalangala Sikkanther Syed Ali ◽

Sanjay R. Mishra

Keyword(s):

Isomer Shift ◽

Cell Volume ◽

Intermetallic Compounds ◽

Unit Cell Volume ◽

Rietveld Analysis ◽

Unit Cell ◽

X Ray Diffraction ◽

X Ray ◽

Arc Melting ◽

Nb Content

Intermetallic compounds of Dy2Fe16Ga1−xNbx (x = 0.0 to 1.00) were synthesized by arc melting. Samples were investigated for structural, magnetic, and hyperfine properties using X-ray diffraction, vibration sample magnetometer, and Mossbauer spectrometer, respectively. The Rietveld analysis of room temperature X-ray diffraction data shows that all the samples were crystallized in Th2Fe17 structure. The unit cell volume of alloys increased linearly with an increase in Nb content. The maximum Curie temperature Tc ~523 K for x = 0.6 sample is higher than Tc = 153 K of Dy2Fe17. The saturation magnetization decreased linearly with increasing Nb content from 61.57 emu/g for x = 0.0 to 42.46 emu/g for x = 1.0. The Mössbauer spectra and Rietveld analysis showed a small amount of DyFe3 and NbFe2 secondary phases at x = 1.0. The hyperfine field of Dy2Fe16Ga1−xNbx decreased while the isomer shift values increased with the Nb content. The observed increase in isomer shift may have resulted from the decrease in s electron density due to the unit cell volume expansion. The substantial increase in Tc of thus prepared intermetallic compounds is expected to have implications in magnets used for high-temperature applications.

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