Kenneth E. Barner

Sol–gel deposition and characterization of Mn2+-doped silicate phosphor films

Abstract Mn 2+ -doped Zn 2 SiO 4 and Mg 2 Gd 8 (SiO 4 ) 6 O 2 phosphor films were deposited on silicon and quartz glass substrates by sol–gel process (dip-coating). The variations of sol viscosity with time and film thickness with the number of layers were investigated in Zn 2 SiO 4 : Mn system. The results of XRD and IR showed that the Zn 2 SiO 4 : Mn films remained amorphous below 700°C and crystallized completely around 1000°C. From AFM studies, it was observed that the grains with 0.5–0.8 μm size packed closely in Zn 2 SiO 4 : Mn films, which were uniform and crack free. The luminescence properties of Zn 2 SiO 4 : Mn films were characterized by absorption, excitation and emission spectra as well as luminescence decay. These properties were discussed in detail by a comparison with those of Mn 2+ (and Pb 2+ )-doped Mg 2 Gd 8 (SiO 4 ) 6 O 2 phosphor films.

Sol–gel synthesis and characterization of Zn2SiO4:Mn phosphor films

Abstract Mn 2+ -doped Zn 2 SiO 4 phosphor films were deposited on silicon and quartz glass substrates by sol–gel method (dip-coating). The variations of sol viscosity with time, film thickness with the number of layers were investigated in the Zn 2 SiO 4 :Mn system. The results of XRD and IR showed that the Zn 2 SiO 4 :Mn films remained amorphous below 700°C and crystallized completely around 1000°C. From AFM studies, it was observed that the grains of 0.5–0.8 μm in size packed closely in Zn 2 SiO 4 :Mn films, which were uniform and crack free. The luminescence properties of Zn 2 SiO 4 :Mn films were characterized by absorption, excitation and emission spectra, as well as luminescence decay.

Hysteresis loops of a ferroelectric superlattice with an antiferroelectric interfacial coupling

By the use of the effective field theory with a probability distribution technique, we apply the transverse spin-1/2 Ising model to study the intrinsic hysteresis of a ferroelectric bilayer with an antiferroelectric interfacial coupling. The effects of the thickness, the interfacial coupling constant, the transverse field and the temperature on the hysteresis are discussed.

Dielectric properties of the BaxSr1−xTiO3 system

We have studied the dielectric properties of the BaxSr1- xTiO3 system within the framework of the transverse spin-1/2 Ising model using the effective field theory with a probability distribution technique that accounts for the self spin correlations. In particular, we have studied the critical temperature Tc(x), the polarization as function of both T and x and also the dielectric susceptibility χ(T, x) for different values of the strength of the applied electric field E.

Critical properties of a ferroelectric superlattice described by a transverse spin-1/2 Ising model

The phase transition properties of a ferroelectric superlattice with two alternating layers A and B described by a transverse spin-1/2 Ising model have been investigated using the effective field theory within a probability distribution technique that accounts for the self spin correlation functions. The Curie temperature Tc, polarization and susceptibility have been obtained. The effects of the transverse field and the ferroelectric and antiferroelectric interfacial coupling strength between two ferroelectric materials are discussed. They relate to the physical properties of antiferroelectric/ferroelectric superlattices.