02286nas a2200217   4500008004100000020001800041245009800059210006900157260009600226300001200322520144500334100002001779700001801799700001401817700001901831700002201850700002501872700002301897700001901920856012901939       2005                        eng d  a1-57498-218-400aMagnetic properties of nanosized ferrite powders synthesized by microwave-hydrothermal method0 aMagnetic properties of nanosized ferrite powders synthesized by   aSan Francisco, CAbAmer Ceramic Soc, 735 Ceramic Place, Westerville, OH 43081-8720 USAcAUG  a143-1483 a<p>Nanosized powders of Fe3O4 and MgFe2O4 are synthesized by microwave-hydrothermal (MH) method. The ferrite powders thus obtained are characterized by powder X-ray diffraction, Mossbauer spectroscopy, scanning and transmission electron microscopies, vibrating sample magnetometer and AC magnetic susceptibility studies. Stoichiometric, nanosized (similar to 34 nm) Fe3O4 particles, having cubic symmetry with a(0) approximate to 8.39 angstrom, are obtained when molar ratio of Fe/NaOH used for the synthesis is 0.133. On the other hand, non-stoichiometric Fe3O4 is obtained when Fe/NaOH molar ratio is increased to 0.4. Though the powder XRD patterns of both stoichiometric and non-stoichiometric Fe3O4 are identical, Mossbauer spectroscopic studies showed different features in terms of asymmetry, intensity, isomer shift, etc. Saturation magnetization, M-s = 70 emu/g and coercivity, H-c = 178 Oe, at room temperature, are obtained for stoichiometric Fe3O4 powders. In the case of MgFe2O4, spherical, nanosized (similar to 3 nm) powders with cubic symmetry (a(0) approximate to 8.30 angstrom) and having very narrow size distribution are obtained under the MH conditions. The temperature and field dependent magnetic measurements on MgFe2O4 powders confirmed the existence of superparamagnetic state in this material with a superparamagnetic blocking temperature of 38 K below which typical magnetic hysteresis behaviour is observed.</p>1 aKhollam, Y., B.1 aDhage, S., R.1 aVerma, S.1 aPotdar, H., S.1 aDeshpande, S., B.1 aJoy, Pattayil, Alias1 aDate, Sadgopal, K.1 aSoohoo, R., F.  uhttps://library.ncl.res.in/content/magnetic-properties-nanosized-ferrite-powders-synthesized-microwave-hydrothermal-method-002266nas a2200169   4500008004100000022001400041245006400055210005800119260022900177300001000406490000800416520151700424100002201941700002001963700001901983856009402002       2011                        eng d  a0015-019300aMicrowave-hydrothermal (MH) synthesis of Ba1-xSrxTiO3 (BST)0 aMicrowavehydrothermal MH synthesis of Ba1xSrxTiO3 BST  a4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLANDbDept Sci & Technol; Defense R& D Org; Council Sci & Ind Res; Mat Res Soc India; Indian Inst Sci; IEEE UFFC; Taylor & Francis Sci Publ; Int Journal FERROELECTcMAR  a39-430 v3273 a<p>The barium-strontium titanate (BST) powders are used in fabrication of various microelectronic devices (because of their field- &amp; composition dependent dielectric properties), integrated capacitors &amp; as thin dielectric layer in DRAM (dynamic random access memories). The utility of MH synthesis route in deriving the BST powders was explored in the present studies under strongly alkaline conditions (pH &gt; 12). Potassium titanyl oxalate (KTO) and nitrates of Ba &amp; Sr were used as the starting precursors and KOH as a mineralizer. The typical BST composition, namely, BST with Sr = 0.25 was chosen for the experimentation. All the MH experiments were carried out in the MARS-5 microwave accelerated digestion system (CEM Corpn., USA). The stoichiometric BST powders were obtained under the MH conditions of 200 degrees C, 200 psi, and 30 min when the Ba/Sr ratio (greater than or similar to 3.25) was kept slightly in excess. The acetic acid treated and water washed MH derived powders showed formation of exclusively cubic BST phase (a(0) = 3.992 A degrees) as confirmed by XRD. These powders were further processed in the form of disks and sintered at high temperature (1350 degrees C/4 h) in air to obtain dense (rho &gt;= 92%) ceramic bodies. Electrical measurements on the lapped and electroded samples (sintered at 1350 degrees C/4h) revealed epsilon(T-c) = 6800, tan delta = 0.1% and T-c = 32 degrees C. These properties are comparable to the reported standard data in the literature.</p>1 aDeshpande, S., B.1 aKhollam, Y., B.1 aPotdar, H., S.  uhttps://library.ncl.res.in/content/microwave-hydrothermal-mh-synthesis-ba1-xsrxtio3-bst-0