An ESR cavity for performing ultimate sensitive ESR spin concentration measurements up to 1300 K

The EPR powder spectra of Gd3+ doped LaA10, are simulated for a number of temperatures between 4 and 800 K by means of the usual spin-Hamiltonian. Values are found for the zero field splitting parameters B(n, 0) only, which agree with single crystal measurements. For an accurate simulation of the axial powder spectra a variable linewidth has to be introduced, because an inhomogeneous broadening of the resonances in the zy plane is observed. This broadening is successfully described by a variable B(2, 2) parameter. This indicates that the Gd3+ ion does not fit within the LaA10, lattice, because GdAlO, is not isostructural with LaAlO,. Crystal field calculations support this assumption.Die EPR-Pulver-Spektren, der mit Gd3+ dotierten Verbindung LaAlO,, werden fur einige Temperaturen zwischen 4 und 800 K mit dem ublichen Spin-Hamiltonoperator simuliert. Nur fur die Nullfeldaufspaltung der Parameter B(n, 0) werden Werte gefunden, die mit Messungen an Einkristallen ubereinstimmen. Um eine gute Simulation der axialen Spektren des Polykristalls zu erhalten, ist eine variable Linienbreite notig, weil eine inhomogene Verbreiterung in der (2, y ) -Ebene beobachtet wird. Diese Verbreiterung wird erfolgreich durch verschiedene B(2,2) Parameter beschrieben. Daraus IaBt sich schlieoen, dao das Gda+-Ion sich nicht in das LaAl0,-Gitter einfugt, da die Gitterstrukturen von GdAlO, und LaA10, nicht ubereinstimmen. Berechnungen des Kristallfeldes unterstutzen diese Behauptung.

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The Simulation and Interpretation of the EPR Powder Spectra of Gd³⁺‐Doped LaAlO₃

Koopmans

Perik

Nieuwenhuijse

et al. 1984

Physica Status Solidi (b)

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High-performance coaxial EPR cavity for investigations at elevated temperatures and pressures

Goldberg

McKinney

1984

Review of Scientific Instruments

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High pressure low temperature ENDOR/EPR cavity Rev. Sci. Instrum. 47, 255 (1976);A microwave cavity suitable for heating a sample to temperatures above 800·C within 15 s at gas pressures above 17.5 MPa is reported. The cavity is coaxial and operates in the TEoll mode at frequencies between 9 and 10 GHz. The heating element is constructed of nickel -chromium (i.e., Chromel) wire. It consists of two concentric helices wound in opposite senses (directions) and connected in series so as to minimize the magnetic field generated by the heater current. The heater is potted in magnesium oxide-phosphate ceramic and placed inside of a cylinder made from 50-llm copper foil which provides uniform temperature distribution and shields the heater from the microwave field. This assembly then serves as the heating element and the coaxial conductor of the cavity. The diameter of the coaxial heater assembly is approximately 7 mm. The sample is confined by a cylindrical quartz cuvette which surrounds the coaxial conductor. Sample thicknesses of 0.2 to 1.0 mm can be used. Heating from room temperature to 800·C requires between 15 and 20 s. Operating pressures up to 17 MPa have been used, although the structural design limit of the brass or beryllium copper walls is greater than 22 MPa. Modulation coils are placed in recessed areas of the cavity walls and covered with a thin layer of copper. Cooling water flows through channels cut into the walls to maintain constant microwave parameters. Q factors of 8000 -12 000 can be obtained depending on the sample.

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High modulation amplitude modification for Varian ESR spectrometers

Goldberg

Lewin

Crandall

1974

Review of Scientific Instruments

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An ESR cavity for performing ultimate sensitive ESR spin concentration measurements up to 1300 K

Cited by 3 publications

References 1 publication

The Simulation and Interpretation of the EPR Powder Spectra of Gd³⁺‐Doped LaAlO₃

The Simulation and Interpretation of the EPR Powder Spectra of Gd³⁺‐Doped LaAlO₃

High-performance coaxial EPR cavity for investigations at elevated temperatures and pressures

High modulation amplitude modification for Varian ESR spectrometers

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Product

Resources

About

An ESR cavity for performing ultimate sensitive ESR spin concentration measurements up to 1300 K

Cited by 3 publications

References 1 publication

The Simulation and Interpretation of the EPR Powder Spectra of Gd3+‐Doped LaAlO3

The Simulation and Interpretation of the EPR Powder Spectra of Gd3+‐Doped LaAlO3

High-performance coaxial EPR cavity for investigations at elevated temperatures and pressures

High modulation amplitude modification for Varian ESR spectrometers

Contact Info

Product

Resources

About

The Simulation and Interpretation of the EPR Powder Spectra of Gd³⁺‐Doped LaAlO₃

The Simulation and Interpretation of the EPR Powder Spectra of Gd³⁺‐Doped LaAlO₃