... ing Studies of the Structure of Substances and Funda-mental Properties of Matter (project no.... more ... ing Studies of the Structure of Substances and Funda-mental Properties of Matter (project no. 14, Ural Div., RAS; contract no. 11/05); and the Swiss Spallation Neutron Source SINQ, Paul Scherrer Institute, Vil-lingen, Switzerland (grant no. II/04 L-56). REFERENCES ...
The effect of oxygen isotope substitution on the alternating-current magnetic susceptibility for ... more The effect of oxygen isotope substitution on the alternating-current magnetic susceptibility for (La1- yPry)0.7Ca0.3MnO3 ceramics (y = 0, 0.25, 0.5, 0.75, 1) was studied in the temperature range 4.2-300 K. At y < 0.75, the low-temperature behaviour of these manganites is typical for a ferromagnetic metal, whereas at y close to 1, the system behaves as an antiferromagnetic charge-ordered insulator.
Journal of Experimental and Theoretical Physics Letters, 1999
A giant isotope effect, wherein the low-temperature metallic state is replaced by an insulator st... more A giant isotope effect, wherein the low-temperature metallic state is replaced by an insulator state, was recently observed when 18O was substituted for 16O in (La0.25Pr0.75)0.7Ca0.3MnO3 [N. A. Babushkina, L. M. Belova, O. Yu. Gorbenko et al., Nature (London) 391, 159 (1998)]. In the present work, the temperature evolution of the magnetic structure of two samples of this compound is studied by neutron diffraction. One sample contained a natural mixture of oxygen isotopes, 99.7% 16O, while the other was enriched to 75% with the isotope 18O. It is established that the samples are crystallographically identical at room temperature. As the temperature decreases, the sample with 16O undergoes successive antiferromagnetic (T AFM=5150 K) and ferromagnetic (T FM=110 K) transitions, which lead to the establishment of a noncollinear ferromagnetic structure, while a purely antiferromagnetic (T AFM=150 K) order arises in the sample with 18O. The temperature dependences of the intensities of the diffraction peaks associated with the charge ordering differ substantially in samples with 16O and 18O, and they correlate with the behavior of their electric resistance and magnetic structure.
Recently, reliable and hermetic joining of stainless steel to niobium pipes has been achieved wit... more Recently, reliable and hermetic joining of stainless steel to niobium pipes has been achieved with the explosive bonding technique. Joining of these two materials are essential to ensure production of a bimetallic transition element of pipe-type for its further use as a part of charged beam acceleration systems of the new generation. A non-destructive neutron diffraction investigation of the tri-axial strains along a radial cross-sectional line through the joint section has been performed. Residual stress results indicate inherently different natures in the residual stress values within the respective pipe sections. In the external stainless steel pipe the residual stresses are tensile, showing a sudden increase to 600 MPa as the interface is approached, whilst being compressive in the internal niobium pipe, not exceeding 650 MPa. A characteristic abrupt stress discontinuity exits at the interface region.
ABSTRACT We describe the synthesis of CeNi3D x deuterides at normal and high deuterium pressures.... more ABSTRACT We describe the synthesis of CeNi3D x deuterides at normal and high deuterium pressures. X-ray and neutron diffraction techniques were used to identify the position and determine the positional parameters of the metal and deuterium atoms. The deuterides are isostructural with the parent compound CeNi3 but have a larger unit cell. Increasing the deuterium content to the composition CeNi3D5.2 leads to partial amorphization of the material. The variation in unit-cell volume observed at low and high deuterium contents indicates that the metal-deuterium bonds are partially ionic and partially metallic.
... ing Studies of the Structure of Substances and Funda-mental Properties of Matter (project no.... more ... ing Studies of the Structure of Substances and Funda-mental Properties of Matter (project no. 14, Ural Div., RAS; contract no. 11/05); and the Swiss Spallation Neutron Source SINQ, Paul Scherrer Institute, Vil-lingen, Switzerland (grant no. II/04 L-56). REFERENCES ...
The effect of oxygen isotope substitution on the alternating-current magnetic susceptibility for ... more The effect of oxygen isotope substitution on the alternating-current magnetic susceptibility for (La1- yPry)0.7Ca0.3MnO3 ceramics (y = 0, 0.25, 0.5, 0.75, 1) was studied in the temperature range 4.2-300 K. At y < 0.75, the low-temperature behaviour of these manganites is typical for a ferromagnetic metal, whereas at y close to 1, the system behaves as an antiferromagnetic charge-ordered insulator.
Journal of Experimental and Theoretical Physics Letters, 1999
A giant isotope effect, wherein the low-temperature metallic state is replaced by an insulator st... more A giant isotope effect, wherein the low-temperature metallic state is replaced by an insulator state, was recently observed when 18O was substituted for 16O in (La0.25Pr0.75)0.7Ca0.3MnO3 [N. A. Babushkina, L. M. Belova, O. Yu. Gorbenko et al., Nature (London) 391, 159 (1998)]. In the present work, the temperature evolution of the magnetic structure of two samples of this compound is studied by neutron diffraction. One sample contained a natural mixture of oxygen isotopes, 99.7% 16O, while the other was enriched to 75% with the isotope 18O. It is established that the samples are crystallographically identical at room temperature. As the temperature decreases, the sample with 16O undergoes successive antiferromagnetic (T AFM=5150 K) and ferromagnetic (T FM=110 K) transitions, which lead to the establishment of a noncollinear ferromagnetic structure, while a purely antiferromagnetic (T AFM=150 K) order arises in the sample with 18O. The temperature dependences of the intensities of the diffraction peaks associated with the charge ordering differ substantially in samples with 16O and 18O, and they correlate with the behavior of their electric resistance and magnetic structure.
Recently, reliable and hermetic joining of stainless steel to niobium pipes has been achieved wit... more Recently, reliable and hermetic joining of stainless steel to niobium pipes has been achieved with the explosive bonding technique. Joining of these two materials are essential to ensure production of a bimetallic transition element of pipe-type for its further use as a part of charged beam acceleration systems of the new generation. A non-destructive neutron diffraction investigation of the tri-axial strains along a radial cross-sectional line through the joint section has been performed. Residual stress results indicate inherently different natures in the residual stress values within the respective pipe sections. In the external stainless steel pipe the residual stresses are tensile, showing a sudden increase to 600 MPa as the interface is approached, whilst being compressive in the internal niobium pipe, not exceeding 650 MPa. A characteristic abrupt stress discontinuity exits at the interface region.
ABSTRACT We describe the synthesis of CeNi3D x deuterides at normal and high deuterium pressures.... more ABSTRACT We describe the synthesis of CeNi3D x deuterides at normal and high deuterium pressures. X-ray and neutron diffraction techniques were used to identify the position and determine the positional parameters of the metal and deuterium atoms. The deuterides are isostructural with the parent compound CeNi3 but have a larger unit cell. Increasing the deuterium content to the composition CeNi3D5.2 leads to partial amorphization of the material. The variation in unit-cell volume observed at low and high deuterium contents indicates that the metal-deuterium bonds are partially ionic and partially metallic.
Uploads