Synthesis of layered perovskite oxides, ACa[sub 2-x]La[sub x]Nb[sub 3-x]Ti[sub x]O[sub 10] (A = K, Rb, Cs), and characterization of new solid acids, HCa[sub 2-x]La[sub x]Nb[sub 3-x]Ti[sub x]O[sub 10] (O < x [le] 2), exhibiting variable Bronsted acidity

Journal Article · Fri Jan 01 04:00:00 EST 1993 · Chemistry of Materials; (United States)

DOI:https://doi.org/10.1021/cm00025a025· OSTI ID:7073497

Gopalakrishnan, J; Uma, S; Bhat, V ^[1]

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1. Indian Institute of Science, Bangalore (India)

Layered perovskite oxides of the formula ACa[sub 2-x]La[sub x]Nb[sub 3-x]Ti[sub x]O[sub 10] (A = K, Rb, Cs and 0 , x [le] 2) have been prepared. The members adopt the structures of the parent ACa[sub 2]Nb[sub 3]O[sub 10]. Interlayer alkali cations in the niobium-titanium oxide series can be ion-exchanged with Li[sup +], Na[sup +], NG[sub 4][sup +], of H[sup +] to give new derivatives. Intercalation of the protonated derivatives with organic bases reveals that the Bronsted acidity of the solid solution series, HCa[sub 2-x]La[sub x]Nb[sub 3-x]Ti[sub x]O[sub 10], depends on the titanium content. While the x = 1 member (HCaLaNb[sub 2]TiO[sub 10]) is nearly as acidic as the parent HCa[sub 2]Nb[sub 3]O[sub 10], the x = 2 member (HLA[sub 2]NbTi[sub 2]O[sub 10]) is a weak acid hardly intercalating organic bases with pK[sub a] [approximately] 11.3. The variation of acidity is probably due to an ordering of Nb/Ti atoms in the triple octahedral perovskite slabs, [Ca[sub 2-x]La[sub x]Nb[sub 3-x]Ti[sub x]O[sub 10]], such that protons are attached to NbO[sub 6] octahedra in the x = 1 member and to TiO[sub 6] octahedra in the x = 2 member. 20 refs., 6 figs., 5 tabs.

• OSTI ID: 7073497
• Journal Information: Chemistry of Materials; (United States), Journal Name: Chemistry of Materials; (United States) Vol. 5:1; ISSN CMATEX; ISSN 0897-4756
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
&amp; Refractories-- Structure &amp; Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical &amp; Physicochemical Properties
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM OXIDES
CESIUM COMPOUNDS
CESIUM OXIDES
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
HYDROGEN COMPOUNDS
INORGANIC ACIDS
ION EXCHANGE MATERIALS
LANTHANUM COMPOUNDS
LANTHANUM OXIDES
MATERIALS
NIOBIUM COMPOUNDS
NIOBIUM OXIDES
OXIDES
OXYGEN COMPOUNDS
POTASSIUM COMPOUNDS
POTASSIUM OXIDES
RARE EARTH COMPOUNDS
REFRACTORY METAL COMPOUNDS
RUBIDIUM COMPOUNDS
RUBIDIUM OXIDES
SYNTHESIS
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS