R. Nath

Abstracts

3 Magnetic Properties of Layered Rare-Earth Oxy-Carbonates Ln2O2CO3 (Ln = Nd, Sm, and Dy)

Authors: R. Nath, U. Arjun, K. Brinda, M. Padmanabhan

Abstract:

Polycrystalline samples of rare-earth oxy-carbonates Ln2O2CO3 (Ln = Nd, Sm, and Dy) are synthesized, and their structural and magnetic properties are investigated. All of them crystallize in a hexagonal structure with space group P6_3/mmc. They form a double layered structure with frustrated triangular arrangement of rare-earth magnetic ions. An antiferromagnetic transition is observed at TN ≈ 1.25 K, 0.61 K, and 1.21 K for Nd2O2CO3, Sm2O2CO3, and Dy2O2CO3, respectively. From the analysis of magnetic susceptibility, the value of the Curie-Weiss temperature θ_CW is obtained to be ≈ 21.7 K, 18 K, and 10.6 K for Nd2O2CO3, Sm2O2CO3, and Dy2O2CO3, respectively. The magnetic frustration parameter f ( = |θ_CW|/T_N) is calculated to be ≈ 17.4, 31, and 8.8 for Nd2O2CO3, Sm2O2CO3, and Dy2O2CO3, respectively which indicates that Sm2O2CO3 is strongly frustrated compared to its Nd and Dy analogues.

Keywords: Chemical Synthesis, Heat Capacity, exchange and superexchange, magnetically ordered materials

Procedia PDF Downloads 146
2 Ferroelectricity in Nano-Composite Films of Sodium Nitrite: Starch Prepared by Drop Cast Technique

Authors: Navneet Dabra, Jasbir S. HUndal, Baljinder Kaur, Lakhbir Singh, V. Annapu Reddy, R. Nath, Dae-Yong Jeong

Abstract:

Nano-composite films of sodium nitrite (NaNO2): Starch with different proportions of NaNO2 and Starch have been prepared by drop cast technique. The ferroelectric hysteresis loops (P-V) have been traced using modified Sawyar-Tower circuit. The films containing equal proportions of NaNO2 and Starch exhibit optimized ferroelectric properties. The stability of the remanent polarization, Pr in the optimized nano-composite films exhibit improved stability over the pure NaNO2 films. The Atomic Force Microscopy (AFM) has been employed to investigate the surface morphology. AFM images clearly reveal the nano sized particles of NaNO2 dispersed in starch with small value of surface roughness.

Keywords: Ferroelectricity, nano-composite films, Atomic Force Microscopy (AFM), nano composite film

Procedia PDF Downloads 308
1 Ferroelectricity in Fused Potassium Nitrate-Polymer Composite Films

Authors: Navneet Dabra, Jasbir S. HUndal, Baljinder Kaur, Lakhbir Singh, V. Annapu Reddy, R. Nath, Dae-Yong Jeong

Abstract:

The ferroelectric properties of fused potassium nitrate (KNO3)- polyvinyl alcohol (PVA) composite films have been investigated. The composite films of KNO3-PVA have been prepared by solvant cast technique and then fused over the brass substrate. The ferroelectric hysteresis loops (P-E) have been obtained at room temperature using modified Sawyer-Tower circuit. Percentage of back switching and differential dielectric constant has been derived from P-V loops. The x-ray diffraction (XRD) studies confirm the formation of ferroelectric phase (phase III) in these composite films. The AFM and FE-SEM studies have been used to study the surface morphology of these composite films. The values of remanemt polarization, coercive field, back switching, crystallite size, lattice parameters, and surface roughness have been estimated and correlated.

Keywords: ferroelectric polymer composite, remanemt polarization, back switching, crystallite size, lattice parameters and surface roughness

Procedia PDF Downloads 256