Hydrothermal crystal growth of the potassium niobate and potassium tantalate family of crystals

Mann, Matthew; Jackson, Summer; Kolis, Joseph W.

doi:10.1016/j.jssc.2010.09.011

Cited by 27 publications

(11 citation statements)

References 47 publications

(52 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However this propensity for phase transition is detrimental to the enhancement of these materials' functionality. For example, efforts to enhance the photocatalytic property of tungstates [1][2][3][4], tantalates [5][6][7][8], vanadates [9][10][11][12][13], and titanates [14][15][16][17][18][19][20] are shown to be limited by the vulnerability of transition prone crystalline phases. Evidently, the slightest phase gradient such as a single intrinsic defect can have significant effects on the functionality of a material because it only takes one to be a charge trap that significantly increases the recombination rates.…”

Section: Introductionmentioning

confidence: 99%

Free energy landscape approach to aid pure phase synthesis of transition metal (X=Cr, Mn and Fe) doped bismuth titanate (Bi2Ti2O7)

Mayfield

Huda

2016

Journal of Crystal Growth

View full text Add to dashboard Cite

A density functional theory study of Cr, Mn and Fe substitutions in Bi 2 Ti 2 O 7 (BTO) photocatalysts is presented. We performed a stability analysis from our total energy calculations and have determined formations of dopant inspired phases are detrimental to the overall photocatalytic performance of X-doped BTO. From our calculated formation energies and electronic structures it is shown that X substitution of Ti is least stable and should be associated with formation of secondary phases more so than X substitution of Bi. This result contradicts the many experimental studies which suggest transition metal dopants always substitute Ti in BTO, but on the other hand, explains the poor photocatalytic response beyond what has become known as the critical dopant concentration.

show abstract

Section: Introductionmentioning

confidence: 99%

Free energy landscape approach to aid pure phase synthesis of transition metal (X=Cr, Mn and Fe) doped bismuth titanate (Bi2Ti2O7)

Mayfield

Huda

2016

Journal of Crystal Growth

View full text Add to dashboard Cite

show abstract

“…Firstly, K 2 Ta 2 O 6 was fabricated from a tantalum sheet by a hydrothermal synthesize with KOH (Kanto Chemical Co. INC., Cica-Reagent, 86.0%) aqueous (deionized water) solution [6][7][8][9][10]. The starting materials for the hydrothermal synthesis were Ta (Nilaco, 99.95%) and KOH.…”

Section: Methodsmentioning

confidence: 99%

Ion-Exchange Reaction Of A-Site In A2Ta2O6 Pyrochlore Crystal Structure

Matsunami¹,

Hashizume²,

Saiki³

2015

Archives of Metallurgy and Materials

View full text Add to dashboard Cite

Na + or K + ion rechargeable battery is started to garner attention recently in Place of Li+ ion cell. It is important that A+ site ion can move in and out the positive-electrode materials. When K 2 Ta 2 O 6 powder had a pyrochlore structure was only dipped into NaOH aqueous solution at room temperature, Na 2 Ta 2 O 6 was obtained. K 2 Ta 2 O 6 was fabricated from a tantalum sheet by a hydrothermal synthesize with KOH aqueous solution. When Na 2 Ta 2 O 6 was dipped into KOH aqueous solution, K 2 Ta 2 O 6 was obtained again. If KTaO 3 had a perovskite structure was dipped, Ion-exchange was not observed by XRD. Because a lattice constant of pyrochlore structure of K-Ta-O system is bigger than perovskite, K + or Na + ion could shinny through and exchange between Ta 5+ and O 2− ion site in a pyrochlore structure. K + or Na + ion exchange of A 2 Ta 2 O 6 pyrochlore had reversibility. Therefore, A 2 Ta 2 O 6 had a pyrochlore structure can be expected such as Na + ion rechargeable battery element.Keywords: K 2 Ta 2 O 6, Na 2 Ta 2 O 6, Ion-exchange, pyrochlore structure, perovskite structure Akumulatory w którym jako nośniki ładunku wykorzystywane są jony Na + lub K + budzą coraz większe zainteresowanie jako alternatywa dla ogniw litowo-jonowych. Należy podkreślić, że kationy w podsieci A + potrafią się przemieszczać z-i do dodatnio naładowanych materiałów elektrodowych. Gdy proszek K 2 Ta 2 O 6 posiadający strukturę pirochloru zanurzono w roztworze wodnym NaOH w temperaturze pokojowej, otrzymano Na 2 Ta 2 O 6 . K 2 Ta 2 O 6 otrzymano poprzez obróbkę arkuszu tantalu metodą hydrotermalną wykorzystując roztwór wodny KOH. Gdy zanurzono Na 2 Ta 2 O 6 w wodnym roztworze KOH, otrzymano z powrotem K 2 Ta 2 O 6 . Natomiast, gdy zanurzono KTaO 3 o strukturze perowskitu, nie obserwowano wymiany jonowej. Dlatego, że stała sieciowa w strukturze pirochloru układu K-Ta-O jest większa niż w przypadku perowskitu, jony K + lub Na + mogą się poruszać i wymieniać w podsieci Ta 5+ i O 2− w pirochlorze. Wymiana jonów K + lub Na + w pirochlorze A 2 Ta 2 O 6 jest odwracalna. Z tego powodu można się spodziewać, że związek A 2 Ta 2 O 6 o strukturze pirochloru może znaleźć potencjalne zastosowanie jako element akumulatora pracującego z jonami Na + .

show abstract

“…The crystal shape grown is rectangular, reflecting the crystal structure. The size of crystals grown by the flux method and the hydrothermal technique is about 2 -4 mm [6,7]. The growth rate of KTaO 3 crystals grown by such solution growth was approximately 0.05 -0.1 mm/h.…”

Section: Introductionmentioning

confidence: 98%

“…Although the primary phase for the stoichiometric melt has been reported to be KTaO 3 [5], KTaO 3 has been recognized as an incongruent material. In fact, KTaO 3 crystal is generally grown by solution growth such as topseeded solution growth (TSSG) [1], the flux method [6] or the hydrothermal technique [7]. The crystal shape grown is rectangular, reflecting the crystal structure.…”

Section: Introductionmentioning

confidence: 99%