Are twins (crystallographic sub-domains) to be expected in synthetic alpha-Quartz?

Why Austenite grains in steel show much more twinning than ferrite grains?

It is oftentimes said to be a distinctive metallographic trait that differentiates a fully austenitic and a fully felly ferritic steel without etching that might distinguish between two. Why...

02 March 2021 728 2 View

How to Eliminate cosine error and abbe error in LASER measurement system(for example Rhenishaw XL80)?

I like to do project in laser measurement system. My objective is to eliminate or reduce the cosine error, abbe error in Laser measurement system. I have Rhenishaw XL80 system. Please tell the...

28 February 2021 4,890 3 View

What could be the reason for not having further low chi square value (better agreement) in my refinement result?

I have tried every combination of parameter changes and after that i have a poor chi square value. I can't get it lower any further. I know there have been a lot of discussion about Rietveld...

26 February 2021 8,480 3 View

How can we limit artifacts caused by rotation in fiber photometry?

We are trying to run fiber photometry experiments for long time scales, but we get these sinusoidal artifacts that come up. We think they may be caused by twisting of the fiber optic subject...

25 February 2021 568 1 View

How to replicate the well conditions of a crystal hit with 20%(w/v) isopropanol?

I had a crystal hit in a well with 0.1M HEPEs pH 7.5, 10%(w/v) PEG 4000, and 20%(w/v) isopropanol. Why is isopropanol in w/v here if it's just solvent? How do I recreate this well condition?

25 February 2021 9,761 1 View

How to measure angle between laser travel path and machine axis in Laser Measurement system?

25 February 2021 1,987 3 View

Can we recognize signs of the "volatility clustering" property of a time series in its time domain plot?

My purpose is to recognize the volatility clustering property without statistical tests such as The Lagrange Multiplier (LM) test.

24 February 2021 4,150 3 View

How can I simulate the optical absorption spectrum of a biomaterial (like DNA or protein) in COMSOL?

I need to simulate the optical properties of a biomaterial, namely DNA, in COMSOL. Basically I need to simulate the IR absorption spectrum of a cylinder filled with a 'concentration' of DNA. I am...

21 February 2021 3,043 3 View

How to overcome convergence issues in concrete arch models?

Hi, I have modelled a three-span arch bridge with soil fill over along with pedestals. The FE modelling is done in LUSAS with HX8M solid elements (i.e. 3D solid modelling). The non-linearity is...

20 February 2021 1,346 2 View

Is there a way to tell based on appearance which protein crystal should diffract the best?

I have had unheard of success with protein crystallography lately from a super successful protein expression and purification batch. I have attained a lately reproducible vast amount of crystals...

09 February 2021 5,155 5 View

Sunao Kurimura

YES.

The paper below will be helpful.

Sunao Kurimura, Masaki Harada, Ken-ichi Muramatsu, Motoi Ueda, Muneyuki Adachi, Tsuyoshi Yamada, Tokio Ueno, "Quartz revisits nonlinear optics: twinned crystal for quasi-phase matching", Optical Materials Express, 1(7), pp.1367-1375, (2011.11)

Thank you.

Sunao

Ravi Ananth

Here is the above reference (PDF):

http://www.opticsinfobase.org/view_article.cfm?gotourl=http%3A%2F%2Fwww%2Eopticsinfobase%2Eorg%2FDirectPDFAccess%2F9B1DCFB2%2DF776%2D46B0%2D91E44D42546FD347%5F224032%2Fome%2D1%2D7%2D1367%2Epdf%3Fda%3D1%26id%3D224032%26seq%3D0%26mobile%3Dno&org=

What are the causes for ASYMMETRY in the Bragg X-ray Rocking Curve Profile (RCP) for a symmetric (004) GaAs reflection?

Real Time Bragg XRD Microscopy with GaAs symmetric (004) Bragg reflection:

http://www.flickr.com/photos/85210325@N04/9430820747/

Is the asymmetry due to:

1. Theory

2. Stacking Faults

3. Twins

4. Dislocations

5. Other defects or causes including instrument & system related?

https://www.researchgate.net/post/What_are_the_causes_for_ASYMMETRY_in_the_Bragg_X-ray_Rocking_Curve_Profile_RCP_for_a_symmetric_004_GaAs_reflection

Here is a LinkedIn "Poll" regarding this issue. Please review and share your experiences.

http://www.linkedin.com/groupItem?view=&gid=2683600&type=member&item=257747275&trk=groups_search_item_list-0-b-ttl&goback=%2Egna_2683600

This is an excellent general reference by Andre Guinier

http://www.flickr.com/photos/85210325@N04/10515372183/

Giovanni Ferraris

Twinning in natural quartz is very common; see e.g http://www.minsocam.org/msa/collectors_corner/arc/qtztwin.htm

Therefore in can be expected in synthetic quartz too. The presence of twinning can be detected by optical and diffraction methods; sometimes, for large crystals, even by morphological features, like re-entrant angles. Optical observation between crossed polarisers of a twin usually shows domains differently illuminated. The diffraction pattern (X-rays, electrons) of a twin shows split spots.