chemistry

LSAT (oxide)

LSAT (oxide) is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand LSAT (oxide) rather than just read about it. In short: LSAT is the most common name for the inorganic compound lanthanum aluminate - strontium aluminium tantalate, which has the chemical formula (LaAlO3)0.3(Sr2TaAlO6)0.7 or its less common alternative: (La0.18Sr0.82)(Al0.59Ta0.41)O3. LSAT is a hard, optically transparent oxide of the elements lanthanum, aluminium, strontium and tantalum.

Key takeaways

LSAT (oxide) belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect LSAT (oxide) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of LSAT (oxide) from memory before moving on to harder problems.

Reference excerpt

LSAT is the most common name for the inorganic compound lanthanum aluminate - strontium aluminium tantalate, which has the chemical formula (LaAlO3)0.3(Sr2TaAlO6)0.7 or its less common alternative: (La0.18Sr0.82)(Al0.59Ta0.41)O3. LSAT is a hard, optically transparent oxide of the elements lanthanum, aluminium, strontium and tantalum. LSAT has the perovskite crystal structure, and its most common use is as a single crystal substrate for the growth of epitaxial thin films.

Background LSAT was originally developed as a substrate for the growth of high Tc cuprate superconductors thin films, mostly of yttrium barium copper oxide (YBCO), for microwave device applications. The motivation for its development was to create a lattice-matched substrate with a similar thermal expansion coefficient and no structural phase transition over a wide temperature range, spanning from the high temperatures used for the growth of cuprates, to the cryogenic temperatures where they are superconducting.

Properties LSAT has a Mohs hardness of 6.5, placing it between quartz and the mineral feldspar. Its relative dielectric constant is ~22 and it has a thermal expansion coefficient of 8~10×10−6/K. The thermal conductivity of LSAT is 5.1 Wm−1K−1. LSAT's (cubic) lattice parameter of 3.868 Å makes it compatible for the growth of a wide range of perovskite oxides with a relatively low strain. LSAT's melting temperature of 1,840C is lower compared to similar alternative substrates, such as LaAlO3. This property enables the growth of LSAT single crystals using the Czochralski process (CZ), which has commercial advantages.

Uses

LSAT is primarily used in its single crystal form, typically as thin (≤1 mm) wafers. These wafers are used as a common substrate for epitaxial growth of thin films. LSAT substrates are popular for epitaxial oxides and their heterostructures, often in the study of electron correlation phenomena. Typical materials grown on LSAT substrates include strontium titanate (SrTiO3), cuprate superconductors (such as YBCO), iron-based superconductors (iron-pnictides), rare-earth manganites, rare-earth nickelates and others. Semiconductors such as gallium nitride can also be grown on LSAT. LSAT's usefulness as a substrate for the growth of such films stems from its high chemical and thermal stability, and very low electrical conductivity. The growth conditions for such epitaxial layers can cause some substrates to form high densities of defects that can alter their properties. One example is the tendency of strontium titanate to form oxygen vacancy defects under high temperatures in high vacuum. These defects result in considerable variations of its properties, including the increase of electrical conductivity and optical opacity. LSAT on the other hand, is stable in both oxidizing and fairly reducing environments in high temperatures, thus enabling a larger window for the processing and growth conditions.

See also Epitaxial growth Electron correlation Strontium titanate Lanthanum aluminate

References

Worked examples

Example 1 — a first encounter with LSAT (oxide)

Start with the simplest possible case. Write down what LSAT (oxide) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to LSAT (oxide) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about LSAT (oxide) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of LSAT (oxide)

In research: LSAT (oxide) appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses LSAT (oxide) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: LSAT (oxide) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aluminates, Aluminium compounds, Inorganic compounds, so understanding it makes those chapters shorter.
In everyday life: Look for LSAT (oxide) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study LSAT (oxide) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what LSAT (oxide) means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain LSAT (oxide) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is LSAT (oxide) in simple terms?

Why does LSAT (oxide) matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study LSAT (oxide)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on LSAT (oxide).